U.S. patent number 11,420,979 [Application Number 16/726,536] was granted by the patent office on 2022-08-23 for organic compound, organic light emitting diode and organic light emitting device having the compound.
This patent grant is currently assigned to LG DISPLAY CO., LTD., SOULBRAIN CO., LTD.. The grantee listed for this patent is LG Display Co., Ltd., Soulbrain Co., Ltd.. Invention is credited to Ik-Rang Choe, Tae-Ryang Hong, Jin Hee Kim, Jun-Yun Kim, Eun Chul Shin.
United States Patent |
11,420,979 |
Choe , et al. |
August 23, 2022 |
Organic compound, organic light emitting diode and organic light
emitting device having the compound
Abstract
Disclosed is an organic compound that includes a fused hetero
aromatic moiety of a spiro structure as an electron donor and a
triazine moiety as an electron acceptor that is linked to the
electron donor via an arylene linker substituted with at least one
electron withdrawing group, an organic light emitting diode and an
organic light emitting device each of which applies the organic
compound into at least one emitting unit. The organic compound
enables the organic light emitting diode to increase its luminous
efficiency and to improve its color purity.
Inventors: |
Choe; Ik-Rang (Paju-si,
KR), Hong; Tae-Ryang (Paju-si, KR), Kim;
Jun-Yun (Paju-si, KR), Kim; Jin Hee (Paju-si,
KR), Shin; Eun Chul (Paju-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG Display Co., Ltd.
Soulbrain Co., Ltd. |
Seoul
Seongnam-si |
N/A
N/A |
KR
KR |
|
|
Assignee: |
LG DISPLAY CO., LTD. (Seoul,
KR)
SOULBRAIN CO., LTD. (Seongnam-si, KR)
|
Family
ID: |
1000006513377 |
Appl.
No.: |
16/726,536 |
Filed: |
December 24, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200199149 A1 |
Jun 25, 2020 |
|
Foreign Application Priority Data
|
|
|
|
|
Dec 24, 2018 [KR] |
|
|
10-2018-0168347 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
51/0094 (20130101); C07D 491/107 (20130101); H01L
51/0067 (20130101); H01L 51/0073 (20130101); H01L
51/0052 (20130101); C07D 495/10 (20130101); C07D
401/10 (20130101); C07D 471/14 (20130101); H01L
51/0072 (20130101); C07F 7/0816 (20130101); H01L
51/0074 (20130101); C07D 471/10 (20130101); C07D
405/14 (20130101); H01L 2251/552 (20130101); H01L
51/5024 (20130101); H01L 51/5004 (20130101) |
Current International
Class: |
H01L
51/00 (20060101); C07D 495/10 (20060101); C07D
491/107 (20060101); C07D 401/10 (20060101); C07F
7/08 (20060101); C07D 471/14 (20060101); C07D
405/14 (20060101); C07D 471/10 (20060101); H01L
51/50 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Woo et al. "Phenazasiline/spiroacridine donor combined with
methyl-substituted linkers for efficient deep blue thermally
activated delayed fluorescence Emitters." ACS applied materials
& interfaces 11, No. 7 (2019): 7199-7207. (Year: 2019). cited
by examiner .
Lin et al., "Sky-Blue Organic Light Emitting Diode with 37%
External Quantum Efficiency Using Thermally Activated Delayed
Fluorescence from Spiroacridine-Triazine Hybrid"., Advanced
Materials, 28, 6976-6983, (2016). cited by applicant.
|
Primary Examiner: Loewe; Robert S
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
The invention claimed is:
1. An organic compound having the following structure of Chemical
Formula 1: ##STR00051## wherein each of R.sub.1 to R.sub.5 is
independently protium, deuterium, tritium, halogen,
C.sub.1.about.C.sub.10 alkyl halide, cyano group, nitro group or a
moiety having the following structure of Chemical Formula 2 or
Chemical Formula 3, wherein at least one of R.sub.1 to R.sub.5 is
selected from the group consisting of halogen,
C.sub.1.about.C.sub.10 alkyl halide, cyano group and nitro group
and at least one of R.sub.1 to R.sub.5 is a moiety of Chemical
Formula 2 or Chemical Formula 3; each of R.sub.6 and R.sub.7 is
independently C.sub.5.about.C.sub.30 aryl group or
C.sub.4.about.C.sub.30 hetero aryl group: ##STR00052## wherein each
of R.sub.8 and R.sub.9 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.1.about.C.sub.20 alkoxy group,
C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30 aryl
group, C.sub.4.about.C.sub.30 hetero aryl group,
C.sub.5.about.C.sub.30 aryl amino group and C.sub.4.about.C.sub.30
hetero aryl amino group, wherein each of the C.sub.5.about.C.sub.30
aryl group, the C.sub.4.about.C.sub.30 hetero aryl group, the
C.sub.5.about.C.sub.30 aryl amino group and the
C.sub.4.about.C.sub.30 hetero aryl amino group is unsubstituted or
substituted with an aromatic group, a hetero aromatic group or a
combination thereof, respectively; each of a and b is a number of a
substituent and is independently an integer of 1 to 3; X in
Chemical Formula 3 is CR.sub.11R.sub.12, NR.sub.13,
SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein each of
R.sub.11 to R.sub.15 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.1.about.C.sub.20 alkoxy group,
C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30 aryl
group and C.sub.4.about.C.sub.30 hetero aryl group.
2. The organic compound of claim 1, wherein the organic compound
has the following structure of Chemical Formula 4: ##STR00053##
wherein R.sub.21 is cyano group; and R.sub.22 is a moiety having
the following structure of Chemical Formula 5 or Chemical Formula
6: ##STR00054## wherein each of R.sub.23 and R.sub.24 is
independently selected from the group consisting of protium,
deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.5.about.C.sub.30 aryl group unsubstituted or substituted with
an aromatic group, a hetero aromatic group or a combination
thereof, and C.sub.4.about.C.sub.30 hetero aryl group unsubstituted
or substituted with an aromatic group, a hetero aromatic group or a
combination thereof; X in Chemical Formula 6 is CR.sub.11R.sub.12,
NR.sub.13, SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein
each of R.sub.11 to R.sub.15 is independently selected from the
group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
3. The organic compound of claim 2, wherein the organic compound
has the following structure of Chemical Formula 7, ##STR00055##
##STR00056## ##STR00057## ##STR00058## ##STR00059## ##STR00060##
##STR00061## ##STR00062## ##STR00063## ##STR00064## ##STR00065##
##STR00066## ##STR00067## ##STR00068## ##STR00069## ##STR00070##
##STR00071## ##STR00072## ##STR00073## ##STR00074## ##STR00075##
##STR00076## ##STR00077## ##STR00078## ##STR00079##
4. The organic compound of claim 2, wherein the organic compound
has a HOMO energy level between about -5.0 and about -6.0 eV, and a
LUMO energy level between about -2.5 and about -3.5 eV; and wherein
an energy bandgap between the HOMO energy level and the LUMO energy
level is between about 2.2 to about 3.0 eV.
5. The organic compound of claim 1, wherein the organic compound
has the following structure of Chemical Formula 8: ##STR00080##
wherein each of R.sub.31 and R.sub.32 is a cyano group; and
R.sub.33 is a moiety having the following structure of Chemical
Formula 9 or Chemical Formula 10: ##STR00081## wherein each of
R.sub.34 and R.sub.35 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.5.about.C.sub.30 aryl group unsubstituted or
substituted with an aromatic group, a hetero aromatic group or a
combination thereof, and C.sub.4.about.C.sub.30 hetero aryl group
unsubstituted or substituted with an aromatic group, a hetero
aromatic group or a combination thereof; X in Chemical Formula 9 is
CR.sub.11R.sub.12, SiR.sub.14R.sub.15, oxygen (O) or sulfur (S),
wherein each of R.sub.11 to R.sub.15 is independently selected from
the group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
6. The organic compound of claim 5, wherein the organic compound
has the following structure of Chemical Formula 11, ##STR00082##
##STR00083## ##STR00084## ##STR00085## ##STR00086## ##STR00087##
##STR00088## ##STR00089## ##STR00090## ##STR00091## ##STR00092##
##STR00093##
7. The organic compound of claim 5, wherein the organic compound
has a HOMO energy level between about -5.0 and about -6.0 eV, and a
LUMO energy level between about -2.5 and about -3.5 eV; and wherein
an energy bandgap between the HOMO energy level and the LUMO energy
level is between about 2.2 to about 3.0 eV.
8. The organic compound of claim 1, wherein the organic compound
has a HOMO energy level between about -5.0 and about -6.0 eV, and a
LUMO energy level between about -2.5 and about -3.5 eV; and wherein
an energy bandgap between the HOMO energy level and the LUMO energy
level is between about 2.2 to about 3.0 eV.
9. An organic light emitting diode, comprising: a first electrode;
a second electrode, wherein the first electrode and second
electrode face each other; and at least one emitting unit
comprising an emitting material layer disposed between the first
and second electrodes, wherein the emitting material layer
comprises an organic compound having the following structure of
Chemical Formula 1: ##STR00094## wherein each of R.sub.1 to R.sub.5
is independently protium, deuterium, tritium, halogen,
C.sub.1.about.C.sub.10 alkyl halide, cyano group, nitro group or a
moiety having the following structure of Chemical Formula 2 or
Chemical Formula 3, wherein at least one of R.sub.1 to R.sub.5 is
selected from the group consisting of halogen,
C.sub.1.about.C.sub.10 to alkyl halide, cyano group and nitro
group, and at least one of R.sub.1 to R.sub.5 is a moiety of
Chemical Formula 2 or Chemical Formula 3; each of R.sub.6 and
R.sub.7 is independently C.sub.5.about.C.sub.30 aryl group or
C.sub.4.about.C.sub.30 hetero aryl group: ##STR00095## wherein each
of R.sub.8 and R.sub.9 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.1.about.C.sub.20 alkoxy group,
C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30 aryl
group, C.sub.4.about.C.sub.3O hetero aryl group,
C.sub.5.about.C.sub.30 aryl amino group and C.sub.4.about.C.sub.30
hetero aryl amino group, wherein each of the C.sub.5.about.C.sub.30
aryl group, the C.sub.4.about.C.sub.30 hetero aryl group, the
C.sub.5.about.C.sub.30 aryl amino group and the
C.sub.4.about.C.sub.30 hetero aryl amino group is unsubstituted or
substituted with an aromatic group, a hetero aromatic group or a
combination thereof, respectively; each of a and b is a number of a
substituent and is independently an integer of 1 to 3; X in
Chemical Formula 3 is CR.sub.11R.sub.12, NR.sub.13,
SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein each of
R.sub.11 to R.sub.15 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.1.about.C.sub.20 alkoxy group,
C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30 aryl
group and C.sub.4.about.C.sub.30 hetero aryl group.
10. The organic light emitting diode of claim 9, wherein the
organic compound has the following structure of Chemical Formula 4:
##STR00096## wherein R.sub.21 is cyano group; and R.sub.22 is a
moiety having the following structure of Chemical Formula 5 or
Chemical Formula 6: ##STR00097## wherein each of R.sub.23 and
R.sub.24 is independently selected from the group consisting of
protium, deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.5.about.C.sub.30 aryl group unsubstituted or substituted with
aromatic group, hetero aromatic group or combination thereof and
C.sub.4.about.C.sub.30 hetero aryl group unsubstituted or
substituted with aromatic group, hetero aromatic group or
combination thereof; X in Chemical Formula 6 is CR.sub.11R.sub.12,
NR.sub.13, SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein
each of R.sub.11 to R.sub.15 is independently selected from the
group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
11. The organic light emitting diode of claim 9, wherein the
organic compound has the following structure of Chemical Formula 8:
##STR00098## wherein each of R.sub.31 and R.sub.32 is cyano group;
and R.sub.33 is a moiety having the following structure of Chemical
Formula 9 or Chemical Formula 10: ##STR00099## wherein each of
R.sub.34 and R.sub.35 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.5.about.C.sub.30 aryl group unsubstituted or
substituted with aromatic group, hetero aromatic group or
combination thereof, and C.sub.4.about.C.sub.30 hetero aryl group
unsubstituted or substituted with aromatic group, hetero aromatic
group or combination thereof; X in Chemical Formula 9 is
CR.sub.11R.sub.12, NR.sub.13, SiR.sub.14R.sub.15, oxygen (O) or
sulfur (S), wherein each of R.sub.11 to R.sub.15 is independently
selected from the group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
12. The organic light emitting diode of claim 9, wherein the
emitting material layer includes a first host and a first dopant,
and wherein the first dopant comprises the organic compound.
13. The organic light emitting diode of claim 12, wherein an energy
level bandgap (|HOMO.sup.H-HOMO.sup.TD|) between a Highest Occupied
Molecular Orbital energy level (HOMO.sup.H) of the first host and a
Highest Occupied Molecular Orbital energy level (HOMO.sup.TD) of
the first dopant or an energy level bandgap
(|LUMO.sup.H-LUMO.sup.TD|) between a Lowest Unoccupied Molecular
Orbital energy level (LUMO.sup.H) of the first host and a Lowest
Unoccupied Molecular Orbital energy level (LUMO.sup.TD) of the
first dopant is equal to or less than about 0.5 eV.
14. The organic light emitting diode of claim 12, wherein each of
an excited state singlet energy level (S.sub.1.sup.H) and an
excited state triplet energy level (T.sub.1.sup.H) of the first
host is higher than each of an excited state singlet energy level
(S.sub.1.sup.TD) and an excited state triplet energy level
(T.sub.1.sup.TD) of the first dopant, respectively.
15. The organic light emitting diode of claim 12, wherein the
emitting material layer further comprises a second dopant, wherein
an excited state triplet energy level (T.sub.1.sup.TD) of the first
dopant is lower than an excited state triplet energy level
(T.sub.1.sup.H) of the first host and an excited state singlet
energy level (S.sub.1.sup.TD) of the first dopant is higher than an
excited state singlet energy level (S.sub.1.sup.FD) of the second
dopant.
16. The organic light emitting diode of claim 9, wherein the
emitting material layer comprises a first emitting material layer
disposed between the first and second electrodes, wherein the first
emitting material comprises the organic compound, wherein the
emitting material layer further comprises a second emitting
material layer disposed between the first electrode and the first
emitting material layer or between the first emitting material
layer and the second electrode.
17. The organic light emitting diode of claim 16, wherein the first
emitting material layer comprises a first host and a first dopant,
and wherein the first dopant comprises the organic compound.
18. The organic light emitting diode of claim 17, wherein the
second emitting material layer comprises a second host and a second
dopant.
19. The organic light emitting diode of claim 18, wherein an
excited state singlet energy level (S.sub.1.sup.TD) of the first
dopant is higher than an excited state singlet energy level
(S.sub.1.sup.FD) of the second dopant.
20. The organic light emitting diode of claim 18, wherein each of
an excited state singlet energy level (S.sub.1.sup.H1) and an
excited state triplet energy level (T.sub.1.sup.H1) of the first
host is higher than each of an excited state singlet energy level
(S.sub.1.sup.TD) and an excited state triplet energy level
(T.sub.1.sup.TD) of the first dopant, respectively, and wherein an
excited state singlet energy level (S.sub.1.sup.H2) of the second
host is higher than an excited state singlet energy level
(S.sub.1.sup.FD) of the second dopant.
21. The organic light emitting diode of claim 18, wherein the
second emitting material layer is disposed between the first
electrode and the first emitting material layer, and wherein the
organic light emitting diode further comprises an electron blocking
layer disposed between the first electrode and the second emitting
material layer.
22. The organic light emitting diode of claim 21, wherein the
second host is the same as a material of the electron blocking
layer.
23. The organic light emitting diode of claim 18, wherein the
second emitting material layer is disposed between the first
emitting material layer and the second electrode, and wherein the
organic light emitting diode further comprises a hole blocking
layer disposed between the second emitting material layer and the
second electrode.
24. The organic light emitting diode of claim 23, wherein the
second host is the same as a material of the hole blocking
layer.
25. The organic light emitting diode of claim 16, wherein the
emitting material layer further comprises a third emitting material
layer disposed opposite to the second emitting material layer with
respect to the first emitting material layer.
26. The organic light emitting diode of claim 25, wherein the first
emitting material layer comprises a first host and a first dopant,
and wherein the first dopant comprises the organic compound.
27. The organic light emitting diode of claim 26, wherein the
second emitting material layer comprises a second host and a second
dopant and the third emitting material layer comprises a third host
and a third dopant.
28. The organic light emitting diode of claim 27, wherein an
excited state singlet energy level (S.sub.1.sup.TD) of the first
dopant is higher than each of excited state singlet energy levels
(S.sub.1.sup.FD1 and S.sub.1.sup.FD2) of the second and third
dopants, respectively.
29. The organic light emitting diode of claim 27, wherein each of
an excited state singlet energy level (S.sub.1.sup.H1) and an
excited state triplet energy level (T.sub.1.sup.H1) of the first
host is higher than each of an excited state singlet energy level
(S.sub.1.sup.TD) and an excited state triplet energy level
(T.sub.1.sup.TD) of the first dopant, respectively, wherein an
excited state singlet energy level (S.sub.1.sup.H2) of the second
host is higher than an excited state singlet energy level
(S.sub.1.sup.FD1) of the second dopant, and wherein an excited
state singlet energy level (S.sub.1.sup.H3) of the third host is
higher than an excited state singlet energy level (S.sub.1.sup.FD2)
of the third dopant.
30. The organic light emitting diode of claim 27, wherein the
second emitting material layer is disposed between the first
electrode and the first emitting material layer and the third
emitting material layer is disposed between the first emitting
material layer and the second electrode, and wherein the organic
light emitting diode further comprises an electron blocking layer
disposed between the first electrode and the second emitting
material layer.
31. The organic light emitting diode of claim 30, wherein the
second host is the same as a material of the electron blocking
layer.
32. The organic light emitting diode of claim 27, wherein the
second emitting material layer is disposed between the first
electrode and the first emitting material layer, and wherein the
third emitting material layer is disposed between the first
emitting material layer and the second electrode, and wherein the
organic light emitting diode further comprises a hole blocking
layer disposed between the third emitting material layer and the
second electrode.
33. The organic light emitting diode of claim 32, wherein the third
host is the same as a material of the hole blocking layer.
34. The organic light emitting diode of claim 33, further
comprising an electron blocking layer disposed between the first
electrode and the second emitting material layer, wherein the
second host is a same as a material of the electron blocking
layer.
35. The organic light emitting diode of claim 9, wherein the at
least one emitting unit includes a first emitting unit disposed
between the first and second electrodes and including a lower
emitting material layer and a second emitting unit disposed between
the first emitting unit and the second electrode and including an
upper emitting material layer, and wherein at least one of the
lower emitting material layer and the upper emitting material layer
includes the organic compound, and further comprises a charge
generation layer disposed between the first and second emitting
units.
36. The organic light emitting diode of claim 35, wherein the
organic compound includes an organic compound having the following
structure of Chemical Formula 4: ##STR00100## wherein R.sub.21 is
cyano group; and R.sub.22 is a moiety having the following
structure of Chemical Formula 5 or Chemical Formula 6: ##STR00101##
wherein each of R.sub.23 and R.sub.24 is independently selected
from the group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.5.about.C.sub.30 aryl
group unsubstituted or substituted with aromatic group, hetero
aromatic group or combination thereof and C.sub.4.about.C.sub.30
hetero aryl group unsubstituted or substituted with aromatic group,
hetero aromatic group or combination thereof; X in Chemical Formula
6 is CR.sub.11R.sub.12, NR.sub.13, SiR.sub.14R.sub.15, oxygen (O)
or sulfur (S), wherein each of R.sub.11 to R.sub.15 is
independently selected from the group consisting of protium,
deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.1.about.C.sub.20 alkoxy group, C.sub.1.about.C.sub.20 silyl
group, C.sub.5.about.C.sub.30 aryl group and C.sub.4.about.C.sub.30
hetero aryl group.
37. The organic light emitting diode of claim 35, wherein the
organic compound includes an organic compound having the following
structure of Chemical Formula 8: ##STR00102## wherein each of
R.sub.31 and R.sub.32 is cyano group; and R.sub.33 is a moiety
having the following structure of Chemical Formula 9 or Chemical
Formula 10: ##STR00103## wherein each of R.sub.34 and R.sub.35 is
independently selected from the group consisting of protium,
deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.5.about.C.sub.30 aryl group unsubstituted or substituted with
aromatic group, hetero aromatic group or combination thereof and
C.sub.4.about.C.sub.30 hetero aryl group unsubstituted or
substituted with aromatic group, hetero aromatic group or
combination thereof; X in Chemical Formula 9 is is
CR.sub.11R.sub.12, NR.sub.13, SiR.sub.14R.sub.15, oxygen (O) or
sulfur (S), wherein each of R.sub.11 to R.sub.15 is independently
selected from the group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
38. The organic light emitting diode of claim 35, wherein at least
one of the lower emitting material layer and the upper emitting
material layer includes a first emitting material layer including
the organic compound and a second emitting material layer disposed
between the first electrode and the first emitting material layer
or between the first emitting material layer and the second
electrode.
39. The organic light emitting diode of claim 38, wherein at least
one of the lower emitting material layer and the upper emitting
material layer further comprises a third emitting material layer
disposed oppositely to the second emitting material layer with
respect to the first emitting material layer.
40. An organic light emitting device, comprising: a substrate; and
the organic light emitting diode according to claim 9 over the
substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit under 35 U.S.C. .sctn. 119(a)
of Korean Patent Application No. 10-2018-0168347, filed in the
Republic of Korea on Dec. 24, 2018, which is incorporated herein by
reference in its entirety.
BACKGROUND
Technical Field
The present disclosure relates to an organic compound, and more
specifically, to an organic compound having enhanced luminous
efficiency, an organic light emitting diode and an organic light
emitting device including the organic compound.
Description of the Related Art
As display devices have become larger, there exists a need for flat
display devices that occupy less space. Among the flat display
devices, a display device using an organic light emitting diode
(OLED) has come into the spotlight.
In the OLED, when electrical charges are injected into an emission
layer between an electron injection electrode (i.e., cathode) and a
hole injection electrode (i.e., anode), electrical charges are
combined to be paired, and then emit light as the combined
electrical charges are disappeared.
The OLED can be formed even on a flexible transparent substrate
such as a plastic substrate. In addition, the OLED can be driven at
a lower voltage of 10 V or less. Besides, the OLED has relatively
low power consumption for driving compared to plasma display panels
and inorganic electroluminescent devices, and a color purity
thereof is very high. Further, since the OLED can display various
colors such as green, blue, red and the like, the OLED display
device has attracted a lot of attention as a next-generation
display device that can replace a liquid crystal display device
(LCD).
BRIEF SUMMARY
Accordingly, the present disclosure is directed to an organic
compound, an organic light emitting diode and an organic light
emitting device including the organic compound that can reduce one
or more of the problems due to the limitations and disadvantages of
the related art.
An object of the present disclosure is to provide an organic
compound that has enhanced luminous efficiency, and an organic
light emitting diode and an organic light emitting device each of
which includes the organic compound in an emitting unit.
Another object of the present disclosure is to provide an organic
compound with improved color purity, and an organic light emitting
diode and an organic light emitting device each of which includes
the organic compound in an emitting unit.
Additional features and advantages of the disclosure will be set
forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
disclosure. The objectives and other advantages of the disclosure
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
According to an aspect, the present disclosure provides an organic
compound having the following Chemical Formula 1:
##STR00001##
wherein each of R.sub.1 to R.sub.5 is independently protium,
deuterium, tritium, halogen, C.sub.1.about.C.sub.10 alkyl halide,
cyano group, nitro group or a moiety having the following structure
of Chemical Formula 2 or Chemical Formula 3, wherein at least one
of R.sub.1 to R.sub.5 is selected from the group consisting of
halogen, C.sub.1.about.C.sub.10 alkyl halide, cyano group and nitro
group and at least one of R.sub.1 to R.sub.5 is a moiety of
Chemical Formula 2 or Chemical Formula 3; each of R.sub.6 and
R.sub.7 is independently C.sub.5.about.C.sub.30 aryl group or
C.sub.4.about.C.sub.30 hetero aryl group:
##STR00002##
wherein each of R.sub.8 and R.sub.9 is independently selected from
the group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group, C.sub.4.about.C.sub.30 hetero aryl group,
C.sub.5.about.C.sub.30 aryl amino group and C.sub.4.about.C.sub.30
hetero aryl amino group, wherein each of the C.sub.5.about.C.sub.30
aryl group, the C.sub.4.about.C.sub.30 hetero aryl group, the
C.sub.5.about.C.sub.30 aryl amino group and the
C.sub.4.about.C.sub.30 hetero aryl amino group is unsubstituted or
substituted with an aromatic group, a hetero aromatic group or a
combination thereof, respectively; each of a and b is a number of a
substituent and is independently an integer of 1 to 3; X in
Chemical Formula 3 is CR.sub.11R.sub.12, NR.sub.13,
SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein each of
R.sub.11 to R.sub.15 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.1.about.C.sub.20 alkoxy group,
C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30 aryl
group and C.sub.4.about.C.sub.30 hetero aryl group.
According to another aspect, the present disclosure provides an
organic light emitting diode (OLED) that comprises a first
electrode; a second electrode facing the first electrode; and at
least one emitting unit including an emitting material layer
disposed between the first and second electrodes, wherein the
emitting material layer comprises the above organic compound.
According to still another aspect, the present disclosure provides
an organic light emitting device that comprises a substrate and the
OLED disposed over the substrate, as described above.
It is to be understood that both the foregoing general description
and the following detailed description are examples and are
explanatory and are intended to provide further explanation of the
disclosure as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the disclosure, are incorporated in and constitute
a part of this specification, illustrate implementations of the
disclosure and together with the description serve to explain the
principles of embodiments of the disclosure.
FIG. 1 is a schematic cross-sectional view illustrating an organic
light emitting display device of the present disclosure.
FIG. 2 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with an exemplary embodiment of
the present disclosure.
FIG. 3 is a schematic diagram illustrating a luminous mechanism of
the delayed fluorescent material in an EML in accordance with an
exemplary embodiment of the present disclosure.
FIG. 4 is a schematic diagram illustrating a luminous mechanism by
energy level bandgaps between luminous materials in accordance with
an exemplary embodiment of the present disclosure.
FIG. 5 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
FIG. 6 is a schematic diagram illustrating a luminous mechanism by
energy level bandgaps among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
FIG. 7 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
FIG. 8 is a schematic diagram illustrating a luminous mechanism by
energy level bandgaps among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
FIG. 9 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
FIG. 10 is a schematic diagram illustrating a luminous mechanism by
energy level bandgaps among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
FIG. 11 is a schematic cross-section view illustrating an organic
light emitting diode in accordance with another exemplary
embodiment of the present disclosure.
DETAILED DESCRIPTION
Reference will now be made in detail to aspects of the disclosure,
examples of which are illustrated in the accompanying drawings.
Organic Compound
An organic compound included in an organic light emitting diode
should have excellent luminous properties and maintain stable
properties during driving the diode. An organic compound of the
present disclosure has a fused hetero aromatic moiety of a spiro
structure as an electron donor and a triazine moiety as an electron
acceptor which is bonded to the electron donor via an aromatic
linker group. The organic compound of the present disclosure has
the following structure of Chemical Formula 1:
##STR00003##
In Chemical Formula 1, each of R.sub.1 to R.sub.5 is independently
protium, deuterium, tritium, halogen, C.sub.1.about.C.sub.10 alkyl
halide, cyano group, nitro group or a moiety having the following
structure of Chemical Formula 2 or Chemical Formula 3. At least one
of R.sub.1 to R.sub.5 is selected from the group consisting of
halogen, C.sub.1.about.C.sub.10 alkyl halide, cyano group and nitro
group. At least one of R.sub.1 to R.sub.5 is a moiety of Chemical
Formula 2 or Chemical Formula 3. Each of R.sub.6 and R.sub.7 is
independently C.sub.5.about.C.sub.30 aryl group or
C.sub.4.about.C.sub.30 hetero aryl group:
##STR00004##
In Chemical Formulae 2 and 3, each of R.sub.8 and R.sub.9 is
independently selected from the group consisting of protium,
deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.1.about.C.sub.20 alkoxy group, C.sub.1.about.C.sub.20 silyl
group, C.sub.5.about.C.sub.30 aryl group, C.sub.4.about.C.sub.30
hetero aryl group, C.sub.5.about.C.sub.30 aryl amino group and
C.sub.4.about.C.sub.30 hetero aryl amino group, wherein each of the
C.sub.5.about.C.sub.30 aryl group, the C.sub.4.about.C.sub.30
hetero aryl group, the C.sub.5.about.C.sub.30 aryl amino group and
the C.sub.4.about.C.sub.30 hetero aryl amino group is unsubstituted
or substituted with an aromatic group, a hetero aromatic group or a
combination thereof, respectively. Each of a and b is a number of a
substituent and is independently an integer of 1 to 3. X in
Chemical Formula 3 is CR.sub.11R.sub.12, NR.sub.13,
SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein each of
R.sub.11 to R.sub.15 is independently selected from the group
consisting of protium, deuterium, tritium, C.sub.1.about.C.sub.20
alkyl group, C.sub.1.about.C.sub.20 alkoxy group,
C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30 aryl
group and C.sub.4.about.C.sub.30 hetero aryl group.
As used herein, the term "unsubstituted" means that hydrogen atom
is bonded, and in this case hydrogen atom includes protium,
deuterium and tritium.
As used herein the term "substituent" may include, but is not
limited to, C.sub.1.about.C.sub.20 alkyl group unsubstituted or
substituted with halogen, C.sub.1.about.C.sub.20 alkoxy group
unsubstituted or substituted with halogen, halogen, cyano group,
--CF.sub.3, hydroxyl group, carboxyl group, carbonyl group, amino
group, C.sub.1.about.C.sub.20 alkyl amino group,
C.sub.5.about.C.sub.30 aryl amino group, C.sub.4.about.C.sub.30
hetero aryl amino group, nitro group, hydrazyl group, sulfonyl
group, C.sub.5.about.C.sub.30 alkyl silyl group,
C.sub.5.about.C.sub.30 alkoxy silyl group, C.sub.3.about.C.sub.30
cycloalkyl silyl group, C.sub.5.about.C.sub.30 aryl silyl group.
C.sub.4.about.C.sub.30 hetero aryl silyl group,
C.sub.5.about.C.sub.30 aryl group and C.sub.4.about.C.sub.30 hetero
aryl group. As an example, when each of R.sub.1 to R.sub.6 is
independently substituted with alkyl group, the alkyl group may be
linear or branched C.sub.1.about.C.sub.20 alkyl group, and
preferably linear or branched C.sub.1.about.C.sub.10 alkyl
group.
As used herein, the term "hetero" described in "hetero aromatic
ring", "hetero aromatic group", "hetero alicyclic ring", "hetero
cyclic alkyl group", "hetero aryl group", "hetero aralkyl group",
"hetero aryloxyl group", "hetero aryl amino group", "hetero arylene
group", "hetero aralkylene group", "hetero aryloxylene group", and
the like means that at least one carbon atoms, for example 1 to 5
carbon atoms, forming such aromatic or alicyclic rings are
substituted with at least one hetero atoms selected from the group
consisting of N, O, S and combination thereof.
In one exemplary embodiment, when each of R.sub.6 and R.sub.7 in
Chemical Formula 1, R.sub.8, R.sub.9 and R.sub.11 to R.sub.15 in
Chemical Formulae 2 and 3 and an aromatic group substituted with
those groups is an aromatic substituent such as
C.sub.5.about.C.sub.30 aryl group, the aromatic substituent may
independently include, but is not limited to, unfused or fused aryl
group such as phenyl, biphenyl, terphenyl, naphthyl, anthracenyl,
pentalenyl, indenyl, indeno-indenyl, heptaleneyl, biphenylenyl,
indacenyl, phenalenyl, phenanthrenyl, benzo-phenanthrenyl,
dibenzo-phenanthrenyl, azulenyl, pyreneyl, fluoranthenyl,
triphenylenyl, chrysenyl, tetraphenyl, tetracenyl, pleiadenyl,
picenyl, pentaphenyl, pentacenyl, fluorenyl, indeno-fluorenyl or
spiro-fluorenyl.
In an alternative embodiment, when each of R.sub.6 and R.sub.7 in
Chemical Formula 1, R.sub.8, R.sub.9 and R.sub.11 to R.sub.15 in
Chemical Formulae 2 and 3 and an aromatic group substituted with
those groups is a hetero aromatic substituent such as
C.sub.4.about.C.sub.30 hetero aryl group, the hetero aromatic
substituent may independently include, but is not limited to,
unfused or fused hetero aryl group such as furanyl, thiophenyl,
pyrrolyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl,
triazinyl, tetrazinyl, imidazolyl, pyrazolyl, indolyl, carbazolyl,
benzo-carbazolyl, dibenzo-carbazolyl, indolo-carbazolyl,
indeno-carbazolyl, benzofuro-carbazolyl, benzothieno-carbazolyl,
quinolinyl, iso-quinolinyl, phthalazinyl, quinoxalinyl, cinnolinyl,
quinazolinyl, benzo-quinolinyl, benzo-iso-quinolinyl,
benzo-quinazolinyl, benzo-quinoxalinyl, acridinyl, phenanthrolinyl,
phenazinyl, phenoxazinyl, phenothiazinyl, pyranyl, oxazinyl,
oxazolyl, iso-oxazolyl, oxadiazolyl, triazolyl, dioxinyl,
benzo-furanyl, dibenzo-furanyl, thiopyranyl, thiazinyl,
benzo-thiophenyl, dibenzo-thiophenyl, spiro-acridinyl connected to
a xanthene, dihydro-acridinyl substituted with at least one
C.sub.1.about.C.sub.10 alkyl group and N-substituted
spiro-fluorenyl.
The organic compound having the structure of Chemical Formula 1
includes a fused hetero aromatic moiety of spiro structure having a
nitrogen atom as an electron donor and a triazine moiety linked to
the electron donor moiety via a phenylene linker. As a streric
hindrance between the electron donor and the electron acceptor
increases, dihedral angles between those moieties increases. As a
result, the organic compound can be divided easily into a highest
occupied molecular orbital (HOMO) energy state and a lowest
unoccupied molecular orbital (LUMO) energy state because the
formation of the conjugate structure between those moieties is
limited.
In addition, dipoles are formed between the electron donor moiety
and the electron acceptor moiety, and the dipole moments within the
molecule are increased. Therefore, an organic light emitting diode
using the organic compound can enhance its luminous efficiency.
Moreover, the organic compound has a limited conformational
structure owing to the fused hetero aromatic moiety of the spiro
structure with a large steric hindrance. As a result, when the
organic compound having the structure of Chemical Formula 1 is
laminated, the conformational structure of the organic compound is
not changed, so the energy loss during the luminescent process is
reduced and the luminescence spectrum of the organic compound can
be limited to a specific range to improve its color purity. As the
luminous efficiency of an OLED using the organic compound is
improved, it is not necessary to increase a driving voltage of the
OLED. Moreover, power consumption of the OLED and load applied to
the OLED, each of which is increased as the driving voltage, can be
reduced, so that the luminous lifetime of the OLED can be
increased.
In one exemplary embodiment, the organic compound having the
structure of Chemical Formula 1 may have one cyano group on the
central phenylene linker. Such an organic compound may have the
following structure of Chemical Formula 4:
##STR00005##
In Chemical Formula 4, R.sub.21 is cyano group. R.sub.22 is a
moiety having the following structure of Chemical Formula 5 or
Chemical Formula 6:
##STR00006##
In Chemical Formulae 5 and 6, each of R.sub.23 and R.sub.24 is
independently selected from the group consisting of protium,
deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.5.about.C.sub.30 aryl group unsubstituted or substituted with
aromatic group, hetero aromatic group or combination thereof and
C.sub.4.about.C.sub.30 hetero aryl group unsubstituted or
substituted with aromatic group, hetero aromatic group or
combination thereof. X in Chemical Formula 6 is CR.sub.11R.sub.12,
NR.sub.13, SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein
each of R.sub.11 to R.sub.15 is independently selected from the
group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
Particularly, the organic compound having one cyano group on the
phenylene linker may have any one of the following structures of
Chemical Formula 7.
##STR00007## ##STR00008## ##STR00009## ##STR00010## ##STR00011##
##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016##
##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021##
##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026##
##STR00027##
In another exemplary embodiment, the organic compound having the
structure of Chemical Formula 1 may have two cyano groups on the
central phenylene linker. Such an organic compound may have the
following structure of Chemical Formula 8:
##STR00028##
In Chemical Formula 8, each of R.sub.31 and R.sub.32 is cyano
group. R.sub.33 is a moiety having the following structure of
Chemical Formula 9 or Chemical Formula 10:
##STR00029##
In Chemical Formulae 9 and 10, each of R.sub.34 and R.sub.35 is
independently selected from the group consisting of protium,
deuterium, tritium, C.sub.1.about.C.sub.20 alkyl group,
C.sub.5.about.C.sub.30 aryl group unsubstituted or substituted with
aromatic group, hetero aromatic group or combination thereof and
C.sub.4.about.C.sub.30 hetero aryl group unsubstituted or
substituted with aromatic group, hetero aromatic group or
combination thereof. X in Chemical Formula 9 is CR.sub.11R.sub.12,
NR.sub.13, SiR.sub.14R.sub.15, oxygen (O) or sulfur (S), wherein
each of R.sub.11 to R.sub.15 is independently selected from the
group consisting of protium, deuterium, tritium,
C.sub.1.about.C.sub.20 alkyl group, C.sub.1.about.C.sub.20 alkoxy
group, C.sub.1.about.C.sub.20 silyl group, C.sub.5.about.C.sub.30
aryl group and C.sub.4.about.C.sub.30 hetero aryl group.
Particularly, the organic compound having two cyano groups on the
phenylene linker may have any one of the following structures of
Chemical Formula 11.
##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034##
##STR00035## ##STR00036## ##STR00037## ##STR00038## [Organic Light
Emitting Device]
The organic compound having the structure of any one in Chemical
Formulae 1, 4, 7, 8 and 11 has a delayed fluorescent property owing
to co-existence of the electron donor moiety and the electron
acceptor moiety within the molecule. The organic compound having
the structure of any one in Chemical Formulae 1, 4, 7, 8 and 11 may
be applied to an emitting material layer of an organic light
emitting diode so as to implement an organic light emitting element
having enhanced luminous efficiency and lower driving voltage.
The organic light emitting diode of the present disclosure may be
applied to an organic light emitting device such as an organic
light emitting display device and an organic light emitting
illumination device. An organic light emitting display device will
be explained. FIG. 1 is a schematic cross-sectional view of an
organic light emitting display device in accordance with an
exemplary embodiment of the present disclosure.
As illustrated in FIG. 1, the organic light emitting display device
100 includes a substrate 102, a thin-film transistor Tr on the
substrate 102, and an organic light emitting diode 200 connected to
the thin film transistor Tr.
The substrate 102 may include, but is not limited to, glass, thin
flexible material and/or polymer plastics. For example, the
flexible material may be selected from the group, but is not
limited to, polyimide (PI), polyethersulfone (PES),
polyethylenenaphthalate (PEN), polyethylene terephthalate (PET),
polycarbonate (PC) and combination thereof. The substrate 102, over
which The thin film transistor Tr and the organic light emitting
diode 200 are arranged, form an array substrate.
A buffer layer 104 may be disposed over the substrate 102, and the
thin film transistor Tr is disposed over the buffer layer 104. The
buffer layer 104 may be omitted.
A semiconductor layer 110 is disposed over the buffer layer 104. In
one exemplary embodiment, the semiconductor layer 110 may include,
but is not limited to, oxide semiconductor materials. In this case,
a light-shield pattern may be disposed under the semiconductor
layer 110, and the light-shield pattern can prevent light from
being incident toward the semiconductor layer 110, and thereby,
preventing the semiconductor layer 110 from being deteriorated by
the light. Alternatively, the semiconductor layer 110 may include,
but is not limited to, polycrystalline silicon. In this case,
opposite edges of the semiconductor layer 110 may be doped with
impurities.
A gate insulating layer 120 formed of an insulating material is
disposed on the semiconductor layer 110. The gate insulating layer
120 may include, but is not limited to, an inorganic insulating
material such as silicon oxide (SiO.sub.x) or silicon nitride
(SiN.sub.x).
A gate electrode 130 made of a conductive material such as a metal
is disposed over the gate insulating layer 120 so as to correspond
to a center of the semiconductor layer 110. While the gate
insulating layer 120 is disposed over a whole area of the substrate
102 in FIG. 1, the gate insulating layer 120 may be patterned
identically as the gate electrode 130.
An interlayer insulating layer 140 formed of an insulating material
is disposed on the gate electrode 130 with covering over an entire
surface of the substrate 102. The interlayer insulating layer 140
may include, but is not limited to, an inorganic insulating
material such as silicon oxide (SiO.sub.x) or silicon nitride
(SiN.sub.x), or an organic insulating material such as
benzocyclobutene or photo-acryl.
The interlayer insulating layer 140 has first and second
semiconductor layer contact holes 142 and 144 that expose both
sides of the semiconductor layer 110. The first and second
semiconductor layer contact holes 142 and 144 are disposed over
opposite sides of the gate electrode 130 with spacing apart from
the gate electrode 130. The first and second semiconductor layer
contact holes 142 and 144 are formed within the gate insulating
layer 120 in FIG. 1. Alternatively, the first and second
semiconductor layer contact holes 142 and 144 are formed only
within the interlayer insulating layer 140 when the gate insulating
layer 120 is patterned identically as the gate electrode 130.
A source electrode 152 and a drain electrode 154, each of which is
made of a conductive material such as a metal, are disposed on the
interlayer insulating layer 140. The source electrode 152 and the
drain electrode 154 are spaced apart from each other with respect
to the gate electrode 130, and contact both sides of the
semiconductor layer 110 through the first and second semiconductor
layer contact holes 142 and 144, respectively.
The semiconductor layer 110, the gate electrode 130, the source
electrode 152 and the drain electrode 154 constitute the thin film
transistor Tr, which acts as a driving element. The thin film
transistor Tr in FIG. 1 has a coplanar structure in which the gate
electrode 130, the source electrode 152 and the drain electrode 154
are disposed over the semiconductor layer 110. Alternatively, the
thin film transistor Tr may have an inverted staggered structure in
which a gate electrode is disposed under a semiconductor layer and
a source and drain electrodes are disposed over the semiconductor
layer. In this case, the semiconductor layer may comprise amorphous
silicon.
A gate line and a data line, which cross each other to define a
pixel region, and a switching element, which is connected to the
gate line and the data line is, may be further formed in the pixel
region. The switching element is connected to the thin film
transistor Tr, which is a driving element. Additionally, a power
line is spaced apart in parallel from the gate line or the data
line, and the thin film transistor Tr may further include a storage
capacitor configured to constantly keep a voltage of the gate
electrode for one frame.
In addition, the organic light emitting display device 100 may
include a color filter for absorbing a part of the light emitted
from the organic light emitting diode 200. For example, the color
filter may absorb a light of specific wavelength such as red (R),
green (G) or blue (B). In this case, the organic light emitting
display device 100 can implement full-color through the color
filter.
For example, when the organic light emitting display device 100 is
a bottom-emission type, the color filter may be disposed on the
interlayer insulating layer 140 with corresponding to the organic
light emitting diode 200. Alternatively, when the organic light
emitting display device 100 is a top-emission type, the color
filter may be disposed over the organic light emitting diode 200,
that is, above a second electrode 220.
A passivation layer 160 is disposed on the source and drain
electrodes 152 and 154 over the whole substrate 102. The
passivation layer 160 has a flat top surface and a drain contact
hole 162 that exposes the drain electrode 154 of the thin film
transistor Tr. While the drain contact hole 162 is disposed on the
second semiconductor layer contact hole 154, it may be spaced apart
from the second semiconductor layer contact hole 154.
The organic light emitting diode 200 includes a first electrode 210
that is disposed on the passivation layer 160 and connected to the
drain electrode 154 of the thin film transistor Tr. The organic
light emitting diode 200 further includes an emitting unit 230 as
an emission layer and a second electrode 220 each of which is
disposed sequentially on the first electrode 210.
The first electrode 210 is disposed in each pixel region. The first
electrode 210 may be an anode and include a conductive material
having a relatively high work function value. For example, the
first electrode 210 may include, but is not limited to, a
transparent conductive material such as indium tin oxide (ITO),
indium zinc oxide (IZO), indium tin zinc oxide (ITZO), tin oxide
(SnO), zinc oxide (ZnO), indium cerium oxide (ICO), aluminum doped
zinc oxide (AZO), and the like.
In one exemplary embodiment, when the organic light emitting
display device 100 is a top-emission type, a reflective electrode
or a reflective layer may be disposed under the first electrode
210. For example, the reflective electrode or the reflective layer
may include, but is not limited to, aluminum-palladium-copper (APC)
alloy.
In addition, a bank layer 170 is disposed on the passivation layer
160 in order to cover edges of the first electrode 210. The bank
layer 170 exposes a center of the first electrode 210.
An emitting unit 230 is disposed on the first electrode 210. In one
exemplary embodiment, the emitting unit 230 may have a mono-layered
structure of an emitting material layer. Alternatively, the
emitting unit 230 may have a multiple-layered structure of a hole
injection layer, a hole transport layer, an electron blocking
layer, an emitting material layer, a hole blocking layer, an
electron transport layer and/or an electron injection layer (See,
FIGS. 2, 5, 7, 9 and 11). In one embodiment, the organic light
emitting diode 200 may have one emitting unit 230. Alternatively,
the organic light emitting diode 200 may have multiple emitting
units 230 to form a tandem structure. The emitting unit 230
includes an organic compound having the structure of any one in
Chemical Formulae 1, 4, 7, 8 and 11. As an example, the organic
compound having the structure of any one in Chemical Formulae 1, 4,
7, 8 and 11 may be used a dopant of an emitting material layer
which may further includes at least one host.
The second electrode 220 is disposed over the substrate 102 above
which the emitting unit 230 is disposed. The second electrode 220
may be disposed over a whole display area and may include a
conductive material with a relatively low work function value
compared to the first electrode 210. The second electrode 220 may
be a cathode. For example, the second electrode 220 may include,
but is not limited to, aluminum (Al), magnesium (Mg), calcium (Ca),
silver (Ag), alloy thereof or combination thereof such as
aluminum-magnesium alloy (Al--Mg).
In addition, an encapsulation film 180 may be disposed over the
second electrode 220 in order to prevent outer moisture from
penetrating into the organic light emitting diode 200. The
encapsulation film 180 may have, but is not limited to, a laminated
structure of a first inorganic insulating film 182, an organic
insulating film 184 and a second inorganic insulating film 186.
The emitting unit 230 of the OLED 200 includes the organic compound
having the structure of any one in Chemical Formulae 1, 4, 7, 8 and
11, as described above. Since the organic compound has both an
electron donor moiety and an electron acceptor moiety, the organic
compound exhibits a delayed fluorescent property. The OLED 200 can
enhance its luminous efficiency and lower its driving voltage so as
to reduce its consumption power by applying the organic compound
having the structure of any one in Chemical Formulae 1, 4, 7, 8 and
11 into the emitting unit 230.
[Organic Light Emitting Diode]
FIG. 2 is a schematic cross-sectional view illustrating an organic
light emitting diode in accordance with an exemplary embodiment of
the present disclosure. As illustrated in FIG. 2, the organic light
emitting diode (OLED) 300 in accordance with the first embodiment
of the present disclosure includes first and second electrodes 310
and 320 facing each other, an emitting unit 330 as an emission
layer disposed between the first and second electrodes 310 and 320.
In one exemplary embodiment, the emitting unit 330 include a hole
injection layer (HIL) 340, a hole transport layer (HTL) 350, an
emitting material layer (EML) 360, an electron transport layer
(ETL) 370 and an electron injection layer (EIL) 380 each of which
is laminated sequentially from the first electrode 310.
Alternatively, the emitting unit 330 may further include a first
exciton blocking layer, i.e. an electron blocking layer (EBL) 355
disposed between the HTL 350 and the EML 360 and/or a second
exciton blocking layer. i.e. a hole blocking layer (HBL) 375
disposed between the EML 360 and the ETL 370.
The first electrode 310 may be an anode that provides a hole into
the EML 360. The first electrode 310 may include, but is not
limited to, a conductive material having a relatively high work
function value, for example, a transparent conductive oxide (TCO).
In an exemplary embodiment, the first electrode 310 may include,
but is not limited to, ITO, IZO, ITZO, SnO, ZnO, ICO, AZO, and the
like.
The second electrode 320 may be a cathode that provides an electron
into the EML 360. The second electrode 320 may include, but is not
limited to, a conductive material having a relatively low work
function values, i.e., a highly reflective material such as Al, Mg,
Ca, Ag, alloy thereof, combination thereof, and the like. As an
example, each of the first and second electrodes 310 and 320 may be
laminated with a thickness of, but not limited to, about 30 nm to
about 300 nm.
The HIL 340 is disposed between the first electrode 310 and the HTL
350 and improves an interface property between the inorganic first
electrode 310 and the organic HTL 350. In one exemplary embodiment,
the HIL 340 may include, but is not limited to,
4,4'4''-Tris(3-methylphenylamino)triphenylamine (MTDATA),
4,4',4''-Tris(N,N-diphenyl-amino)triphenylamine (NATA),
4,4',4''-Tris(N-(naphthalene-1-yl)-N-phenyl-amino)triphenylamine
(1T-NATA),
4,4',4''-Tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine
(2T-NATA), Copper phthalocyanine (CuPc),
Tris(4-carbazoyl-9-yl-phenyl)amine (TCTA),
N,N'-Diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4''-diamine
(NPB; NPD), 1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile
(Dipyrazino[2,3-f:2'3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile;
HAT-CN), 1,3,5-tris[4-(diphenylamino)phenyl]benzene (TDAPB),
poly(3,4-ethylenedioxythiphene)polystyrene sulfonate (PEDOT/PSS)
and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 340 may be omitted in compliance with a
structure of the OLED 300.
The HTL 350 is disposed adjacently to the EML 360 between the first
electrode 310 and the EML 360. In one exemplary embodiment, the HTL
350 may include, but is not limited to,
N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine
(TPD), NPB, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP),
Poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine]
(Poly-TPD),
Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphe-
nylamine))] (TFB), Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane
(TAPC),
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
.
In one exemplary embodiment, each of the HIL 340 and the HTL 350
may be laminated with a thickness of, but is not limited to, about
5 nm to about 200 nm, and preferably about 5 nm to about 100
nm.
The EML 360 may include a host doped with a dopant where a
substantial light emission is occurred. In this exemplary
embodiment, the EML 360 may include a host (a first host) doped
with a dopant (a first dopant). For example, the organic compound
having the structure of any one in Chemical Formulae 1, 4, 7, 8 and
11 may be used as a delayed fluorescent dopant (dopant 1 or T
dopant) in the EML 360. The EML 360 may emit light of green color.
The configuration and energy levels among the luminous materials in
the EML 360 will be explained in more detail.
The ETL 370 and the EIL 380 are laminated sequentially between the
EML 360 and the second electrode 320. The ETL 370 may include a
material having high electron mobility so as to provide electrons
stably with the EML 360 by fast electron transportation.
In one exemplary embodiment, the ETL 370 may include, but is not
limited to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the like.
As an example, the ETL 370 may include, but is not limited to,
tris-(8-hydroxyquinoline aluminum (Alq.sub.3),
2-biphenyl-4-yl-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD),
spiro-PBD, lithium quinolate (Liq),
1,3,5-Tris(N-phenylbenzimidazol-2-yl)benzene (TPBi),
Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1'-biphenyl-4-olato)alumin-
um (BAlq), 4,7-diphenyl-1,10-phenanthroline (Bphen),
2,9-Bis(naphthalene-2-yl)4,7-diphenyl-1,10-phenanthroline (NBphen),
2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),
3-(4-Biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ),
4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),
1,3,5-Tri(p-pyrid-3-yl-phenyl)benzene (TpPyPB),
2,4,6-Tris(3'-(pyridin-3-yl)biphenyl-3-yl)1,3,5-triazine
(TmPPPyTz),
Poly[9,9-bis(3'-(N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene]-alt-
-2,7-(9,9-dioctylfluorene)] (PFNBr) and/or tris(phenylquinoxaline)
(TPQ).
The EIL 380 is disposed between the second electrode 320 and the
ETL 370, and can improve physical properties of the second
electrode 320 and therefore, can enhance the life span of the OLED
300. In one exemplary embodiment, the EIL 380 may include, but is
not limited to, an alkali halide such as LiF, CsF, NaF, BaF.sub.2
and the like, and/or an organic metal compound such as lithium
benzoate, sodium stearate, and the like.
As an example, each of the ETL 370 and the EIL 380 may be laminated
with a thickness of, but is not limited to, about 10 nm to about
100 nm.
When holes are transferred to the second electrode 320 via the EML
360 and/or electrons are transferred to the first electrode 310 via
the EML 360, the luminous lifetime and the luminous efficiency of
the OLED 300 may be reduced. In order to prevent those phenomena,
the OLED 300 in accordance with this embodiment of the present
disclosure has at least one exciton blocking layer disposed
adjacently to the EML 360.
For example, the OLED 300 of the exemplary embodiment includes the
EBL 355 between the HTL 350 and the EML 360 so as to control and
prevent electron transfers. In one exemplary embodiment, the EBL
355 may include, but is not limited to, TCTA,
Tris[4-(diethylamino)phenyl]amine,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, 1,3-bis(carbazol-9-yl)benzene
(mCP), 3,3'-bis(N-carbazolyl)-1,1'-biphenyl (mCBP), CuPc,
N,N'-bis[4-(bis(3-methylphenyl)amino)phenyl]-N,N'-diphenyl[1,1'-biphenyl]-
-4,4'-diamine (DNTPD), TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene, and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole.
In addition, the OLED 300 further includes the HBL 375 as a second
exciton blocking layer between the EML 360 and the ETL 370 so that
holes cannot be transferred from the EML 360 to the ETL 370. In one
exemplary embodiment, the HBL 375 may include, but is not limited
to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds, and
triazine-based compounds.
For example, the HBL 375 may include a compound having a relatively
low HOMO energy level compared to the emitting material in EML 360.
The HBL 375 may include, but is not limited to, BCP, BAlq,
Alq.sub.3, PBD, spiro-PBD, Liq,
Bis-4,5-(3,5-di-3-pyridylphenyl)-2-methylpyrimidine (B3 PYMPM),
Oxybis(2,1-phenylene))bis(diphenylphosphine oxide (DPEPO),
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof.
As described schematically above, the EML 360 of the OLED 300 in
accordance with the first embodiment of the present disclosure
include a host, and a dopant having a delayed fluorescent property
(T dopant), which is the organic compound having the structure of
any one in Chemical Formulae 1, 4, 7, 8 and 11. When the EML 360
includes the dopant having the delayed fluorescent property, the
OLED 300 improves its luminous efficiency and its luminous lifetime
and has a lower driving voltage.
An Organic Light Emitting Diode (OLED) emits light as holes
injected from the anode and electrons injected from the cathode are
combined to form excitons in EML, and then unstable excited state
excitons return to a stable ground state. Theoretically, when
electrons meet holes to form exciton, a singlet exciton of a paired
spin and a triplet exciton of an unpaired spin are produced by a
ratio of 1:3 by spin arrangements. Only the singlet exciton among
the excitons can be involved in emission process in case of
fluorescent materials. Accordingly, the OLED may exhibit luminous
efficiency by maximum 5% in case of using the common fluorescent
material.
In contrast, phosphorescent materials use different luminous
mechanism of converting both singlet excitons and triplet exciton
into light. The phosphorescent materials can convert singlet
excitons into triplet excitons through intersystem crossing (ISC).
Therefore, it is possible to enhance luminous efficiency in case of
applying the phosphorescent materials that use both the singlet
excitons and the triplet excitons during the luminous process
compared to the fluorescent materials. However, prior art blue
phosphorescent materials exhibits too low of a color purity to use
with the display device and exhibits a very short luminous
lifetime, and therefore, they have not been used in commercial
display devices.
A delayed fluorescent material, which can solve the limitations
accompanied by the prior art fluorescent dopants and the
phosphorescent dopants, has been developed recently. Representative
delayed fluorescent material is a thermally-activated delayed
fluorescent (TADF) material. Since the delayed fluorescent material
generally has both an electron donor moiety and an electron
acceptor moiety within its molecular structure, its triplet exciton
energy can be converted upwardly to an intramolecular charge
transfer (ICT) state. In case of using the delayed fluorescent
material as a dopant, it is possible to use both the excitons of
singlet energy level S.sub.1 and the excitons of triplet energy
level T.sub.1 during the emission process.
The luminous mechanism of the delayed fluorescent material will be
explained with referring to FIG. 3, which is a schematic diagram
illustrating a luminous mechanism of the delayed fluorescent
material in an EML in accordance with another exemplary embodiment
of the present disclosure. As illustrated in FIG. 3, both the
excitons of singlet energy level S.sub.1.sup.TD and the excitons of
triplet energy level T.sub.1.sup.TD in the delayed fluorescent
material can move to an intermediate energy level state, i.e. ICT
state, and then the intermediate stated excitons can be transferred
to a ground state (S.sub.0; S1.fwdarw.ICT.rarw.T.sub.1). Since the
excitons of singlet energy level S.sub.1.sup.TD as well as the
excitons of triplet energy level T.sub.1.sup.TD in the delayed
fluorescent material are involved in the emission process, the
delayed fluorescent material has improved luminous efficiency.
Because both the HOMO and the LUMO are widely distributed over the
whole molecule within the common fluorescent material, it is not
possible to inter-convert between the singlet energy level and the
triplet energy level within it (selection rule). In contrast, since
the delayed fluorescent material, which can be converted to ICT
state, has little orbital overlaps between HOMO and LUMO, there is
little interaction between the HOMO state molecular orbital and the
LUMO state molecular orbital in the state where dipole moment is
polarized within the delayed fluorescent material. As a result, the
changes of spin states of electrons does not have an influence on
other electrons, and a new charge transfer band (CT band) that does
not follow the selection rule is formed in the delayed fluorescent
material.
In other words, since the delayed fluorescent material has the
electron acceptor moiety spacing apart from the electron donor
moiety within the molecule, it exists as a polarized state having a
large dipole moment within the molecule. As the interaction between
HOMO molecular orbital and LUMO molecular orbital becomes little in
the state where the dipole moment is polarized, both the triplet
energy level excitons and the singlet energy level excitons can be
converted to ICT state. Accordingly, the excitons of triplet energy
level T.sub.1 as well as the excitons of singlet energy level
S.sub.1 can be involved in the emission process.
In case of driving the diode that includes the delayed fluorescent
material, 25% excitons of singlet energy level S.sub.1.sup.TD and
75% excitons of triplet energy level T.sub.1.sup.TD are converted
to ICT state by heat or electrical field, and then the converted
excitons transfer to the ground state S.sub.0 with luminescence.
Therefore, the delayed fluorescent material may have 100% internal
quantum efficiency in theory.
The delayed fluorescent material must have an energy level bandgap
.DELTA.E.sub.ST.sup.TD equal to or less than about 0.3 eV, for
example, from about 0.05 to about 0.3 eV, between the singlet
energy level S.sub.1.sup.TD and the triplet energy level
T.sub.1.sup.TD so that exciton energy in both the singlet energy
level and the triplet energy level can be transferred to the ICT
state. The material having little energy level bandgap between the
singlet energy level S.sub.1.sup.TD and the triplet energy level
T.sub.1.sup.TD can exhibit common fluorescence in which the
excitons of singlet energy level S.sub.1.sup.TD can be transferred
to the ground state S.sub.0, as well as delayed fluorescence with
Reverse Inter System Crossing (RISC) in which the excitons of
triplet energy level T.sub.1.sup.TD can be transferred upwardly to
the excitons of singlet energy level S.sub.1.sup.TD, and then the
exciton of singlet energy level S.sub.1.sup.TD transferred from the
triplet energy level T.sub.1.sup.TD can be transferred to the
ground state S.sub.0.
The delayed fluorescent material can realize identical quantum
efficiency as the prior art phosphorescent material including heavy
metals because the delayed fluorescent material can obtain a
theoretical luminous efficiency up to 100%. The host for
implementing the delayed fluorescence can induce triplet exciton
energy generated at the delayed fluorescent material to be involved
in the luminous process without quenching as a non-emission. In
order to induce such exciton energy transfer, energy levels among
the host and the delayed fluorescent material should be
adjusted.
FIG. 4 is a schematic diagram illustrating a luminous mechanism by
energy level bandgaps between luminous materials in accordance with
an exemplary embodiment of the present disclosure. As illustrated
schematically in FIG. 4, each of an excited state singlet energy
level S.sub.1.sup.H and an excited state triplet energy level
T.sub.1.sup.H of the host should be higher than each of an excited
state singlet energy level S.sub.1.sup.TD and an excited state
triple energy level T.sub.1.sup.TD of the dopant, which has the
delayed fluorescent property and is the organic compound having the
structure of any one in Chemical Formulae 1, 4, 7, 8 and 11,
respectively. For example, the excited triplet energy level
T.sub.1.sup.H of the host may be higher than the excited state
triplet energy level T.sub.1.sup.TD of the dopant by at least about
0.2 eV.
As an example, when the excited state triplet energy level
T.sub.1.sup.H of the host is not sufficiently higher than the
excited state triplet energy levels of the dopant, which may be a
delayed fluorescent material, the excitons of the triplet state
level T.sub.1.sup.H of the dopant can be reversely transferred to
the excited state triplet energy level T.sub.1.sup.H of the host,
which cannot utilize triplet exciton energy. Accordingly, the
excitons of the triplet state level T.sub.1.sup.TD of the dopant
having the delayed fluorescent property may be quenched as a
non-emission and the triplet state excitons of the dopant cannot be
involved in the emission. As an example, the host may have an
excited state singlet energy level S.sub.1.sup.H of equal to or
more than about 2.8 eV and an excited state triplet energy level
T.sub.1.sup.H of equal to or more than about 2.6 eV, but are not
limited thereto.
The dopant (TD), which has the delayed fluorescent material, which
may be the organic compound having the structure of any one in
Chemical Formulae 1, 4, 7, 8 and 11, should have an energy level
bandgap .DELTA.E.sub.ST.sup.TD between the excited stated singlet
energy level S.sub.1.sup.TD and the excited state triplet energy
level T.sub.1.sup.TD equal to or less than about 0.3 eV, for
example between about 0.05 and about 0.3 eV, in order to realize
delayed fluorescence (See, FIG. 3).
In addition, it is necessary to adjust properly HOMO energy levels
and LUMO energy levels of the host and the dopant, which may be the
fluorescent material. For example, it is preferable that an energy
level bandgap (|HOMO.sup.H-HOMO.sup.TD|) between a HOMO energy
level (HOMO.sup.H) of the host and a HOMO energy level
(HOMO.sup.TD) of the dopant, or an energy level bandgap
(|LUMO.sup.H-LUMO.sup.TD|) between a LUMO energy level (LUMO.sup.H)
of the host and a LUMO energy level (LUMO.sup.TD) of the dopant may
be equal to or less than about 0.5 eV, for example, between about
0.1 eV to about 0.5 eV. In this case, the charges can be
transported efficiently from the host to the first dopant and
thereby enhancing an ultimate luminous efficiency.
Moreover, an energy level bandgap (Eg.sup.H) between the HOMO
energy level (HOMO.sup.H) and the LUMO energy level (LUMO.sup.H) of
the host may be larger than an energy level bandgap (Eg.sup.TD)
between the HOMO energy level (HOMO.sup.TD) and the LUMO energy
level (LUMO.sup.TD) of the dopant. As an example, the HOMO energy
level (HOMO.sup.H) of the host is deeper or lower than the HOMO
energy level (HOMO.sup.TD) of the dopant, and the LUMO energy level
(LUMO.sup.H) of the host is shallower or higher than the LUMO
energy level (LUMO.sup.TD) of the dopant.
In one exemplary embodiment, the organic compound having the
structure of any one in Chemical Formulae 1, 4, 7, 8 and 11, as the
dopant having the delayed fluorescent dopant, may have a HOMO
energy level (HOMO.sup.TD) between about -5.0 and about -6.0 eV,
and preferably between about -5.0 and about -5.5 eV and a LUMO
energy level (LUMO.sup.TD) between about -2.5 and about -3.5 eV,
and preferably about -2.5 and about -3.0 eV. Also, an energy level
bandgap (Eg.sup.TD) between those HOMO and LUMO energy levels of
the organic compound may be between about 2.2 to about 3.0 eV, and
preferably about 2.4 and about 2.8 eV. In addition, the host may
have a HOMO energy level (HOMO') between about -5.0 and about -6.5
eV, and preferably between about -5.5 and about -6.2 eV and a LUMO
energy level (LUMO.sup.TD) between about -1.5 and about -3.0 eV,
and preferably about -1.5 and about -2.0 eV. Also, an energy level
bandgap (Eg.sup.H) between those HOMO and LUMO energy levels of the
host may be between about 3.0 to about 4.0 eV, and preferably about
3.0 and about 3.5 eV.
In one exemplary embodiment, the host in the EML 360 may include,
but is not limited to,
9-(3-(9H-carbazol-9-yl)phenyl)-9H-carbazole-3-carbonitrile
(mCP-CN), CBP, mCBP, mCP, DPEPO,
2,8-bis(diphenylphosphoryl)dibenzothiophene (PPT),
1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB),
2,6-di(9H-carbazol-9-yl)pyridine (PYD-2Cz),
2,8-di(9H-carbazol-9-yl)dibenzothiophene (DCzDBT),
3',5'-Di(carbazol-9-yl)-[1,1'-bipheyl]-3,5-dicarbonitrile (DCzTPA),
4-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile (pCzB-2CN),
3'-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile (mCzB-2CN),
diphenyl-4-triphenylsilylphenyl-phosphine oxide (TSPO1),
9-(9-phenyl-9H-carbazol-6-yl)-9H-carbazole (CCP),
9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9'-bicarbazole and/or
4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.
When the EML 360 includes the host and the dopant, i.e. the organic
compound having the structure of any one in Chemical Formulae 1, 4,
7, 8 and 11, the weight ratio of the host may be equal to or more
than the weight ratio of the dopant. As an example, the EML 360 may
include the dopant of about 1 to about 50% by weight, preferably of
about 10 to about 40% by weight, and more preferably of about 20 to
about 40% by weight. The EML 360 may be laminated with a thickness
of, but is not limited to, about 10 nm to about 200 nm, preferably
about 20 nm to about 100 nm, and more preferably about 30 nm to
about 50 nm.
In the above first embodiment, the EML 360 includes only one dopant
having the delayed fluorescent property. Unlike that embodiment,
the EML may include plural dopants having different luminous
properties. FIG. 5 is a schematic cross-sectional view illustrating
an organic light emitting diode in accordance with another
exemplary embodiment of the present disclosure. As illustrated in
FIG. 5, the OLED 300A according to the second embodiment of the
present disclosure includes first and second electrodes 310 and 320
facing each other and an emitting unit 330a disposed between the
first and second electrodes 310 and 320.
In one exemplary embodiment, the emitting unit 330a as an emission
layer includes a HIL 340, a HTL 350, an EML 360a, an ETL 370 and an
EIL 380 each of which is laminated sequentially over the first
electrode 310. Alternatively, the emitting unit 330a may further
include a first exciton blocking layer, i.e. an EBL 355 disposed
between the HTL 350 and the EML 360a and/or a second exciton
blocking layer, i.e. a HBL 375 disposed between the EML 360a and
the ETL 370. The emitting unit 330a may have the same
configurations and materials as the emitting unit 330 in FIG. 2
except the EML 360a.
The EML 360a may include a host (a first host), a first dopant and
a second dopant. The first dopant may be a delayed fluorescent
dopant (T dopant; TD) and the second dopant may be a fluorescent
dopant (F dopant; FD). In this case, the organic compound having
the structure of any one in Chemical Formulae 1, 4, 7, 8 and 11 may
be used as the first dopant and a fluorescent or phosphorescent
material may be sued as the second dopant. The OLED 300A can
implement hyper-fluorescence enhancing its luminous efficiency by
adjusting energy levels among the luminous materials, i.e. the host
and the dopants.
FIG. 6 is a schematic diagram illustrating luminous mechanism by
energy level bandgap among luminous materials in accordance with
another exemplary embodiment of the present disclosure.
When an EML includes only the dopant which has the delayed
fluorescent property and has the structure of any one in Chemical
Formula 1, 4, 7, 8 and 11, the EML may implement high internal
quantum efficiency as the prior art phosphorescent materials
including heavy metals because the dopant can exhibit 100% internal
quantum efficiency in theory.
However, because of the bond formation between the electron
acceptor and the electron donor and conformational twists within
the delayed fluorescent material, additional charge transfer
transition (CT transition) within the delayed fluorescent material
is caused thereby, and the delayed fluorescent material have
various geometry. As a result, the delayed fluorescent materials
show emission spectra having very broad FWHM (full-width at half
maximum) in the course of emission, which results in poor color
purity. In addition, the delayed fluorescent material utilizes the
triplet exciton energy as well as the singlet exciton energy in the
luminous process with rotating each moiety within its molecular
structure, which results in twisted internal charge transfer
(TICT). As a result, the luminous lifetime of an OLED including
only the delayed fluorescent materials may be reduced owing to
weakening of molecular bonding forces among the delayed fluorescent
materials.
In the second embodiment, the EML 360a further includes the second
dopant, which may be a fluorescent or phosphorescent material, in
order to prevent the color purity and luminous lifetime from being
reduced in case of using only the delayed fluorescent materials.
The triplet exciton energy of the first dopant (T dopant), which
may be the delayed fluorescent material, is converted upwardly to
the singlet exciton energy of its own by RISC mechanism, then the
converted singlet exciton energy of the first dopant can be
transferred to the second dopant (F dopant), which may be the
fluorescent or phosphorescent material, in the same EML 360a by
Dexter energy transfer mechanism, which transfer exciton energies
depending upon wave function overlaps among adjacent molecules by
inter-molecular electron exchanges and exciton diffusions.
When the EML 360a includes the host, the first dopant (T dopant)
which may be the organic compound having the structure of any one
in Chemical Formulae 1, 4, 7, 8 and 11 and having the delayed
fluorescent property and the second dopant (F dopant) which may be
the fluorescent or phosphorescent material, it is necessary to
adjust properly energy levels amount those luminous materials.
An energy level bandgap between an excited state singlet energy
level S.sub.1.sup.TD and an excited state triplet energy level
T.sub.1.sup.TD of the first dopant (T dopant), which is the organic
compound having the structure of any one in Chemical Formulae 1, 4,
7, 8 and 11, may be equal to or less than about 0.3 eV in order to
realize the delayed fluorescence. In addition, each of an excited
state singlet energy level S.sub.1.sup.H and an excited state
triplet energy level T.sub.1.sup.H of the host is higher than each
of the excited state singlet energy level S.sub.1.sup.TD and the
excited state triplet energy level T.sub.1.sup.TD of the first
dopant, respectively. As an example, the excited state triplet
energy level T.sub.1.sup.H of the host may be higher than the
excited state triplet energy level T.sub.1.sup.TD of the first
dopant by at least about 0.2 eV. Moreover, the excited state
triplet energy level T.sub.1.sup.TD of the first dopant is higher
than an excited state triplet energy level T.sub.1.sup.FD of the
second dopant. In one exemplary embodiment, the excited state
singlet energy level S.sub.1.sup.TD of the first dopant may be
higher than an excited state singlet energy level S.sub.1.sup.FD of
the second dopant as a fluorescent material.
In addition, an energy level bandgap (|HOMO.sup.H-HOMO.sup.TD|)
between a HOMO energy level (HOMO.sup.H) of the host and a HOMO
energy level (HOMO.sup.TD) of the first dopant, or an energy level
bandgap (|LUMO.sup.H-LUMO.sup.TD|) between a LUMO energy level
(LUMO.sup.H) of the host and a LUMO energy level (LUMO.sup.TD) of
the first dopant may be equal to or less than about 0.5 eV.
For example, the host may include, but is not limited to, mCP-CN,
CBP, mCBP, mCP, DPEPO, PPT, TmPyPB. PYD-2Cz, DCzDBT, DCzTPA,
pCzB-2CN, mCzB-2CN, TSPO1, CCP,
9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9'-bicabazole and/or
4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.
The exciton energy should be effectively transferred from the first
dopant as the delayed fluorescent material to the second dopant as
the fluorescent or phosphorescent material in order to implement
hyper-fluorescence. With regard to energy transfer efficiency from
the delayed fluorescent material to the fluorescent or
phosphorescent material, an overlap between an emission spectrum of
the delayed fluorescent material and an absorption spectrum of the
fluorescent or phosphorescent material can be considered. As an
example, a fluorescent or phosphorescent material having an
absorption spectrum with overlapping area with an emission spectrum
of the first dopant, i.e. the organic compound having the structure
of any one in Chemical Formulae 1, 4, 7, 8 and 11, may be used as
the second dopant in order to transfer exciton energy efficiently
from the first dopant to the second dopant.
In one exemplary embodiment, the fluorescent material as the second
dopant may have, but is not limited to, quinolino-acridine core. As
an example, the second dopant having the quinolino-acridine core
may include 5,12-dimethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.3 eV; T.sub.1: 2.0 eV; LUMO: -3.0 eV; HOMO:
-5.4 eV), 5,12-diethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.3 eV; T.sub.1: 2.2 eV; LUMO: -3.0 eV; HOMO:
-5.4 eV),
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S.sub.1: 2.2 eV; T.sub.1: 2.0 eV; LUMO: -3.1 eV; HOMO:
-5.5 eV),
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(-
5H, 12H)-dione(S.sub.1: 2.2 eV; T.sub.1: 2.0 eV; LUMO: -3.1 eV;
HOMO: -5.5 eV),
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione(S: 2.0 eV; T.sub.1: 1.8 eV; LUMO: -3.3 eV; HOMO: -5.5
eV).
In addition, the fluorescent material as the second dopant may
include, but is not limited to,
1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)eth-
enyl]-4H-pyran-4-ylidene}propanedinitrile(DCJTB; S.sub.1: 2.3 eV;
T.sub.1: 1.9 eV; LUMO: -3.1 eV; HOMO: -5.3 eV). Moreover, metal
complexes which can emit light of green color may be used as the
second dopant.
In one exemplary embodiment, the weight ratio of the host may be
larger than the weight ratio of the first and second dopants in the
EML 360a, and the weight ratio of the first dopant may be larger
larger than the weight ratio of the second dopant. In an
alternative embodiment, the weight ratio of the host is larger than
the weight ratio of the first dopant and the weight ratio of the
first dopant is larger than the weight ratio of the second dopant.
When the weight ratio of the first dopant is larger than the weight
ratio of the second dopant, excition energy can be transferred
enough from the first dopant to the second dopant by Dexter energy
transfer mechanism. As an example, the EML 360a includes the host
of about 60 to about 75% by weight, the first dopant of about 20 to
about 40% by weight and the second dopant of about 0.1 to about 5%
by weight.
The OLEDs in accordance with the previous embodiments have a
single-layered EML. Alternatively, an OLED in accordance with the
present disclosure may include multiple-layered EML. FIG. 7 is a
schematic cross-sectional view illustrating an organic light
emitting diode having a double-layered EML in accordance with
another exemplary embodiment of the present disclosure. FIG. 8 is a
schematic diagram illustrating luminous mechanism by energy level
bandgap among luminous materials in accordance with another
exemplary embodiment of the present disclosure.
As illustrated in FIG. 7, the OLED 400 in accordance with an
exemplary third embodiment of the present disclosure includes first
and second electrodes 410 and 420 facing each other and an emitting
unit 430 as an emission layer disposed between the first and second
electrodes 410 and 420.
In one exemplary embodiment, the emitting unit 430 includes an HIL
440, an HTL 450, and EML 460, an ETL 470 and an EIL 480 each of
which is laminated sequentially over the first electrode 410. In
addition, the emitting unit 430 may further include an EBL 455 as a
first exciton blocking layer disposed between the HTL 450 and the
EML 460, and/or an HBL 475 as a second exciton blocking layer
disposed between the EML 460 and the ETL 470.
As described above, the first electrode 410 may be an anode and may
include, but is not limited to, a conductive material having a
relatively large work function values such as ITO, IZO, SnO, ZnO,
ICO, AZO, and the like. The second electrode 420 may be a cathode
and may include, but is not limited to, a conductive material
having a relatively small work function values such as Al, Mg, Ca,
Ag, alloy thereof or combination thereof.
The HIL 440 is disposed between the first electrode 410 and the HTL
450. The HIL 440 may include, but is not limited to, MTDATA. NATA,
1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSS
and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 440 may be omitted in compliance with the
structure of the OLED 400.
The HTL 450 is disposed adjacently to the EML 460 between the first
electrode 410 and the EML 460. The HTL 450 may include, but is not
limited to, aromatic amine compounds such as TPD, NPD(NPB), CBP,
poly-TPD, TFB, TAPC,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
.
The EML 460 includes a first EML (EML1) 462 and a second EML (EML2)
464. The EML1 462 is disposed between the EBL 455 and the HBL 475
and the EML2 464 is disposed between the EML1 462 and the HBL 475.
One of the EML1 462 and the EML2 464 includes a first dopant (T
dopant) having a delayed fluorescent property, for example, an
organic compound having the structure of any one in Chemical
Formulae 1, 4, 7, 8 and 11, the other of the EML 1462 and the EML2
464 includes a second dopant (F dopant) as a fluorescent or
phosphorescent material. The configuration and energy levels among
the luminous materials in the EML 460 will be explained in more
detail below.
The ETL 470 is disposed between the EML 460 and the EIL 480. In one
exemplary embodiment, the ETL 470 may include, but is not limited
to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the like. As an example, the ETL 470
may include, but is not limited to, Alq.sub.3, PBD, spiro-PBD, Liq,
TPBi, BAlq, Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB, TmPPPyTz, PFNBr
and/or TPQ.
The EIL 480 is disposed between the second electrode 420 and the
ETL 470. In one exemplary embodiment, the EIL 480 may include, but
is not limited to, an alkali halide such as LiF, CsF, NaF,
BaF.sub.2, and the like, and/or an organic metal compound such as
lithium benzoate, sodium stearate, and the like.
The EBL 455 is disposed between the HTL 450 and the EML 460 for
controlling and preventing electron transportations between the HTL
450 and the EML 460. As an example, The EBL 455 may include, but is
not limited to, TCTA, Tris[4-(diethylamino)phenyl]amine,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole.
The HBL 475 is disposed between the EML 460 and the ETL 470 for
preventing hole transportations between the EML 460 and the ETL
470. In one exemplary embodiment, the HBL 475 may include, but is
not limited to, oxadiazole-based compounds, triazole-based
compounds, phenanthroline-based compounds, benzoxazole-based
compounds, benzothiazole-based compounds, benzimidazole-based
compounds, and triazine-based compounds. As an example, the HBL 475
may include a compound having a relatively low HOMO energy level
compared to the emitting material in EML 460. The HBL 475 may
include, but is not limited to, BCP, BAlq, Alq.sub.3, PBD,
spino-PBD, Liq, B3PYMPM, DPEPO,
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof.
In the exemplary third embodiment, the EML1 462 includes a first
host and a first dopant, which is a delayed fluorescent material
and the EML 464 includes a second host and a second dopant, which
is a fluorescent or phosphorescent material.
The EML1 462 includes the first host and the first dopant which is
the delayed fluorescent material, i.e. the organic compound having
the structure of any one in Chemical Formulae 1, 4, 7, 8 and 11. An
energy level bandgap (.DELTA.E.sub.ST.sup.TD) between the excited
state singlet energy level S.sub.1.sup.TD and the excited state
triplet energy level T.sub.1.sup.TD of the first dopant is very
small (.DELTA.E.sub.ST.sup.TD is equal to or less than about 0.3
eV; See, FIG. 3) so that triplet exciton energy of the first dopant
can be transferred to the singlet exciton energy of its own by RISC
mechanism. While the first dopant has high internal quantum
efficiency, but it has poor color purity due to its wide FWHM
(full-width half maximum).
On the contrary, the EML2 464 may include the second host and the
second dopant as a fluorescent material. While the second dopant as
a fluorescent material has advantage in terms of color purity due
to its narrow FWHM, but its internal quantum efficiency is low
because its triplet exciton cannot be involved in a luminous
process.
However, in this exemplary embodiment, the singlet exciton energy
and the triplet exciton energy of the first dopant, which has the
delayed fluorescent property, in the EML 1 462 can be transferred
to the second dopant, which may be the fluorescent or
phosphorescent material, in the EML2 464 disposed adjacently to the
EML1 462 by FRET (Forster resonance energy transfer) mechanism,
which transfers energy non-radially through electrical fields by
dipole-dipole interactions. Accordingly, the ultimate emission
occurs in the second dopant within the EML2 464.
In other words, the triplet exciton energy of the first dopant is
converted upwardly to the singlet exciton energy of its own in the
EML1 462 by RISC mechanism. Then, the converted singlet exciton
energy of the first dopant is transferred to the singlet exciton
energy of the second dopant because the excited state singlet
energy level S.sub.1.sup.TD of the first dopant is higher than the
excited state singlet energy level S.sub.1.sup.TD of the second
dopant (See, FIG. 8). The second dopant in the EML2 464 can emit
light using the triplet exciton energy as well as the singlet
exciton energy.
As the exciton energy, which is generated at the first dopant as
the delayed fluorescent material in the EML1 462, is efficiently
transferred from the first dopant to the second dopant in the EML2
464, a hyper-fluorescence can be realized. In this case, the first
dopant only acts as transferring exciton energy to the second
dopant. Substantial light emission is occurred in the EML2 464
including the second dopant which is the fluorescent or
phosphorescent dopant and has a narrow FWHM. Accordingly, the OLED
400 can enhance its quantum efficiency and improve its color purity
due to narrow FWHM.
Each of the EML1 462 and the EML2 464 includes the first host and
the second host, respectively. The exciton energies generated at
the first and second hosts should be transferred to the first
dopant as the delayed fluorescent material to emit light. It is
necessary to adjust energy levels among the luminous materials in
order to realize a hyper-fluorescence.
As illustrated in FIG. 8, each of excited state singlet energy
levels S.sub.1.sup.H1 and S.sub.1.sup.H2 and excited state triplet
energy levels T.sub.1.sup.H1 and T.sub.1.sup.H2 of the first and
second hosts should be higher than each of the excited state
singlet energy level S.sub.1.sup.TD and the excited state triplet
energy level T.sub.1.sup.TD of the first dopant as the delayed
fluorescent material, respectively.
For example, when each of the excited triplet energy levels
T.sub.1.sup.H1 and T.sub.1.sup.H2 of the first and second hosts is
not high enough than the excited state triplet energy level
T.sub.1.sup.TD of the first dopant, the triplet exciton of the
first dopant may be reversely transferred to the excited state
triplet energy levels T.sub.1.sup.H1 and T.sub.1.sup.H2 of the
first and second hosts, which cannot utilize triplet exciton
energy. Accordingly, the excitons of the triplet state level
T.sub.1.sup.TD of the first dopant may be quenched as a
non-emission and the triplet state excitons of the first dopant
cannot be involved in the emission. As an example, each of the
excited state triplet energy levels T.sub.1.sup.H1 and
T.sub.1.sup.H2 of the first and second hosts may be higher than the
excited state triplet energy level T.sub.1.sup.TD of the first
dopant by at least about 0.2 eV.
The excited state singlet energy level S.sub.1.sup.H2 of the second
host is higher than an excited state singlet energy level
S.sub.1.sup.FD of the second dopant. In this case, the singlet
exciton energy generated at the second host can be transferred to
the excited singlet energy level S.sub.1.sup.FD of the second
dopant.
In addition, it is necessary for the EML 460 to implement high
luminous efficiency and color purity as well as to transfer exciton
energy efficiently from the first dopant, which is converted to ICT
complex state by RISC mechanism in the EML1 462, to the second
dopant which is the fluorescent or phosphorescent material in the
EML2 464. In order to realize such an OLED 400, the excited state
triplet energy level T.sub.1.sup.TD of the first dopant is higher
than an excited state triplet energy level T.sub.1.sup.FD of the
second dopant. In one exemplary embodiment, the excited state
singlet energy level S.sub.1.sup.TD of the first dopant is higher
than an excited state singlet energy level S.sub.1.sup.FD of the
second dopant as a fluorescent material.
In one exemplary embodiment, the energy level bandgap between the
excited state singlet energy level S.sub.1.sup.TD and the excited
state triplet energy level T.sub.1.sup.TD of the first dopant may
be equal to or less than about 0.3 eV. In addition, an energy level
bandgap (|HOMO.sup.H-HOMO.sup.TD|) between a HOMO energy level
(HOMO.sup.H) of the first and/or second hosts and a HOMO energy
level (HOMO.sup.TD) of the first dopant, or an energy level bandgap
(|LUMO.sup.H-LUMO.sup.TD|) between a LUMO energy level (LUMO.sup.H)
of the first and/or second hosts and a LUMO energy level
(LUMO.sup.TD) of the first dopant may be equal to or less than
about 0.5 eV.
When the luminous materials do not satisfy the required energy
levels as described above, exciton energies are quenched at the
first and second dopants or exciton energies cannot transferred
efficiently from the host to the dopants, so that OLED 400 may have
reduced quantum efficiency.
The first host and the second host may be the same or different
from each other. For example, each of the first host and the second
host may independently include, but is not limited to, mCP-CN, CBP,
mCBP, mCP, DPEPO, PPT, TmPyPB, PYD-2Cz. DCzDBT, DCzTPA, pCzB-2CN,
mCzB-2CN, TSPO1, CCP,
9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9'-bicarbazole and/or
4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.
The second dopant may have narrow FWHM and have luminous spectrum
having large overlapping area with the absorption spectrum of the
first dopant. As an example, the second dopant may include, but is
not limited to, an organic compound having a quinolino-acridine
core such as 5,12-dimethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, 5,12-diethylquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-]acridine-7,14(5H,
12H)-dione, DCJTB and any metal complexes which can emit light of
green color.
In one exemplary embodiment, each of the first and second hosts in
the EML1 462 or the EML2 464 may have weight ratio equal to or more
than the first dopant and the second dopant in the same EMLs 462
and 464, respectively. In addition, the weight ratio of the first
dopant in the EML1 462 may be larger than the weight ratio of the
second dopant in the EML2 464. In this case, it is possible to
transfer enough exciton energy from the first dopant in the EML1
462 to the second dopant in the EML2 464.
Particularly, the weight ratio of the first host may be equal to or
more than the weight ratio of the first dopant in the EML1 462. As
an example, the EML1 462 may include the first host of about 50 to
about 90% by weight, preferably about 60 to about 90% by weight,
and more preferably about 60 to about 80% by weight, and the first
dopant of about 1 to about 50% by weight, preferably about 10 to
about 40% by weight, and more preferably about 20 to about 40% by
weight.
The weight ratio of the second host may be more than the weight
ratio of the second dopant in the EML2 464. As an example, the EML2
464 may include the second host of about 90 to about 99% by weight,
and preferably about 95 to about 99% by weight and the second
dopant of about 1 to about 10% by weight, and preferably about 1 to
about 5% by weight.
Each of the EML1 462 and the EML2 464 may be laminated with a
thickness of, but is not limited to, about 5 to about 100 nm,
preferably about 10 nm to about 30 nm, and more preferably about 10
nm to about 20 nm.
When the EML2 464 is disposed adjacently to the HBL 475 in one
exemplary embodiment, the second host, which is included in the
EML2 464 together with the second dopant, may be the same material
as the HBL 475. In this case, the EML2 464 may have a hole blocking
function as well as an emission function. In other words, the EML2
464 can act as a buffer layer for blocking holes. In one
embodiment, the HBL 475 may be omitted where the EML2 464 may be a
hole blocking layer as well as an emitting material layer.
When the EML2 464 is disposed adjacently to the EBL 455 in another
exemplary embodiment, the second host may be the same material as
the EBL 455. In this case, the EML2 464 may have an electron
blocking function as well as an emission function. In other words,
the EML2 464 can act as a buffer layer for blocking electrons. In
one embodiment, the EBL 455 may be omitted where the EML2 464 may
be an electron blocking layer as well as an emitting material
layer.
An OLED having a triple-layered EML will be explained. FIG. 9 is a
schematic cross-sectional view illustrating an organic light
emitting diode having a triple-layered EML in accordance with
another exemplary embodiment of the present disclosure. FIG. 10 is
a schematic diagram illustrating luminous mechanism by energy level
bandgap among luminous materials in accordance with another
exemplary embodiment of the present disclosure.
As illustrated in FIG. 9, an OLED 500 in accordance with the fourth
embodiment of the present disclosure includes first and second
electrodes 510 and 520 facing each other and an emitting unit 530
as an emission layer disposed between the first and second
electrodes 510 and 520.
In one exemplary embodiment, the emitting unit 530 includes an HIL
540, an HTL 550, and EML 560, an ETL 570 and an EIL 580 each of
which is laminated sequentially over the first electrode 510. In
addition, the emitting unit 530 may further include an EBL 555 as a
first exciton blocking layer disposed between the HTL 550 and the
EML 560, and/or an HBL 575 as a second exciton blocking layer
disposed between the EML 560 and the ETL 570.
As described above, the first electrode 510 may be an anode and may
include, but is not limited to, a conductive material having a
relatively large work function values such as ITO, IZO, SnO, ZnO,
ICO, AZO, and the like. The second electrode 520 may be a cathode
and may include, but is not limited to, a conductive material
having a relatively small work function values such as Al, Mg, Ca,
Ag, alloy thereof or combination thereof.
The HIL 540 is disposed between the first electrode 510 and the HTL
550. The HIL 540 may include, but is not limited to, MTDATA, NATA,
1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN, TDAPB, PEDOT/PSS
and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 540 may be omitted in compliance with the
structure of the OLED 500.
The HTL 550 is disposed adjacently to the EML 560 between the first
electrode 510 and the EML 560. The HTL 550 may include, but is not
limited to, aromatic amine compounds such as TPD, NPD(NPB), CBP,
poly-TPD, TFB, TAPC,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
.
The EML 560 includes a first EML (EML1) 562, a second EML (EML2)
564 and a third EML (EML3) 566. The EML1 562 is disposed between
the EBL 555 and the HBL 575, the EML2 564 is disposed between the
EBL 555 and the EML1 562 and the EML3 566 is disposed between the
EML1 562 and the HBL 575. The configuration and energy levels among
the luminous materials in the EML 560 will be explained in more
detail below.
The ETL 570 is disposed between the EML 560 and the EIL 580. In one
exemplary embodiment, the ETL 570 may include, but is not limited
to, oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the like. As an example, the ETL 570
may include, but is not limited to, Alq.sub.3, PBD, spiro-PBD, Liq,
TPBi, BAlq, Bphen. NBphen. BCP, TAZ, NTAZ, TpPyPB, TmPPPyTz, PFNBr
and/or TPQ.
The EIL 580 is disposed between the second electrode 520 and the
ETL 570. In one exemplary embodiment, the EIL 580 may include, but
is not limited to, an alkali halide such as LiF, CsF, NaF,
BaF.sub.2 and the like, and/or an organic metal compound such as
lithium benzoate, sodium stearate, and the like.
The EBL 555 may be disposed between the HTL 550 and the EML 560 for
controlling and preventing electron transportations between the HTL
550 and the EML 560. As an example, The EBL 555 may include, but is
not limited to, TCTA, Tris[4-(diethylamino)phenyl]amine,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, mCP, mCBP, CuPe, DNTPD, TDAPB,
2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole.
The HBL 575 may be disposed between the EML 560 and the ETL 570 for
preventing hole transportations between the EML 560 and the ETL
570. In one exemplary embodiment, the HBL, 575 may include, but is
not limited to, oxadiazole-based compounds, triazole-based
compounds, phenanthroline-based compounds, benzoxazole-based
compounds, benzothiazole-based compounds, benzimidazole-based
compounds, and triazine-based compounds. As an example, the HBL 575
may include a compound having a relatively low HOMO energy level
compared to the emitting material in EML 560. The HBL 575 may
include, but is not limited to, BCP, BAlq, Alq.sub.3, PBD,
spiro-PBD, Liq, B3PYMPM, DPEPO,
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof.
The EML1 562 includes a first dopant (T dopant) having a delayed
fluorescent property, i.e. the organic compound having the
structure of any one in Chemical Formulae 1, 4, 7, 8 and 11. Each
of the EML2 564 and the EML3 566 includes a second dopant (a first
fluorescent or phosphorescent dopant, F dopant 2) and a third
dopant (a second fluorescent or phosphorescent dopant). Each of the
EML1 562, EML2 564 and EML3 566 further includes a first host, a
second host and a third host, respectively.
In accordance with this embodiment, the singlet energy as well as
the triplet energy of the first dopant (T dopant) as the delayed
fluorescent material, i.e. the organic compound having the
structure of any one in Chemical Formulae 1, 4, 7, 8 and 11 in the
EML1 562 can be transferred to the second and third dopants (F
dopants 1 and 2) each of which is included in the EML2 564 and EML3
566 disposed adjacently to the EML1 562 by FRET energy transfer
mechanism. Accordingly, the ultimate emission occurs in the second
and third dopants in the EML2 564 and the EML3 566.
In other words, the triplet exciton energy of the first dopant is
converted upwardly to the singlet exciton energy of its own in the
EML1 562 by RISC mechanism, then the singlet exciton energy of the
first dopant is transferred to the singlet exciton energy of the
second and third dopants in the EML2 564 and the EML3 566 because
the excited state singlet energy level S.sub.1.sup.TD of the first
dopant is higher than each of the excited state singlet energy
levels S.sub.1.sup.FD1 and S.sub.1.sup.FD2 of the second and third
dopants (See, FIG. 10). The singlet exciton energy of the first
dopant in the EML1 562 is transferred to the second and third
dopants in the EML2 564 and the EML3 566 which are disposed
adjacently to the EML1 562 by FRET mechanism.
The second and third dopants in the EML2 564 and EML3 566 can emit
light using the singlet exciton energy and the triplet exciton
energy derived from the first dopant. Each of the second and third
dopants may have narrower FWHM compared to the first dopant. As the
exciton energy, which is generated at the first dopant as the
delayed fluorescent material in the EML1 562, is transferred to the
second and third dopants in the EML2 564 and the EML3 566, a
hyper-fluorescence can be realized. In this case, the first dopant
only acts as transferring energy to the second and third dopants.
The EML1 562 including the first dopant is not involved in the
ultimate emission process. Substantial light emission is occurred
in the EML2 564 and in the EML3 566 each of which includes the
second dopant and the third dopant with a narrow FWHM. Accordingly,
the OLED 500 can enhance its quantum efficiency and improve its
color purity due to narrow FWHM. As an example, each of the second
and third dopants may have an emission wavelength range having a
large overlapping area with an absorption wavelength range of the
first dopant, so that exciton energy of the first dopant may be
transferred efficiently to each of the second and third
dopants.
In this case, it is necessary to adjust properly energy levels
among the hosts and the dopants in the EML1 562, the EML2 564 and
the EML3 566. As illustrated in FIG. 10, each of excited state
singlet energy levels S.sub.1.sup.H1, S.sub.1.sup.H2 and
S.sub.1.sup.H3 and excited state triplet energy levels
T.sub.1.sup.H1, T.sub.1.sup.H2 and T.sub.1.sup.H3 of the first to
third hosts should be higher than each of the excited state singlet
energy level S.sub.1.sup.TD and the excited state triplet energy
level T.sub.1.sup.TD of the first dopant as the delayed fluorescent
material, respectively.
For example, when each of the excited triplet energy levels
T.sub.1.sup.H1, T.sub.1.sup.H2 and T.sub.1.sup.H3 of the first to
third hosts is not high enough than the excited state triplet
energy level T.sub.1.sup.TD of the first dopant, the triplet
exciton of the first dopant may be reversely transferred to the
excited state triplet energy levels T.sub.1.sup.H1, T.sub.1.sup.H2
and T.sub.1.sup.H3 of the first to third hosts, which cannot
utilize triplet exciton energy. Accordingly, the excitons of the
triplet state level T.sub.1.sup.TD of the first dopant may be
quenched as a non-emission and the triplet state excitons of the
first dopant cannot be involved in the emission. As an example,
each of the excited state triplet energy levels T.sub.1.sup.H1,
T.sub.1.sup.H2 and T.sub.1.sup.H3 of the first to third hosts may
be higher than the excited state triplet energy level
T.sub.1.sup.TD of the first dopant by at least about 0.2 eV.
In addition, it is necessary for the EML 560 to implement high
luminous efficiency and color purity as well as to transfer exciton
energy efficiently from the first dopant, which is converted to ICT
complex state by RISC mechanism in the EML1 562, to the second and
third dopants each of which is the fluorescent or phosphorescent
material in the EML2 564 and the EML3 566. In order to realize such
an OLED 500, the excited state triplet energy level T.sub.1.sup.TD
of the first dopant in the EML1 562 is higher than each of excited
state triplet energy levels T.sub.1.sup.FD1 and T.sub.1.sup.FD2 of
the second and third dopants. In one exemplary embodiment, the
excited state singlet energy level S.sub.1.sup.TD of the first
dopant may be higher than each of excited state singlet energy
levels S.sub.1.sup.FD1 and S.sub.1.sup.D2 of the second and third
dopants as fluorescent material.
Moreover, the exciton energy, which is transferred from the first
dopant to each of the second and third dopants, should not be
transferred to the second and third hosts in order to realize
efficient light emission. As an example, each of the excited
singlet energy levels S.sub.1.sup.H2 and S.sub.1.sup.H3 of the
second and third hosts may be higher than each of the excited state
energy level S.sub.1.sup.FD1 and S.sub.1.sup.FD2 of the second and
third dopants, respectively. In one exemplary embodiment, the
energy level bandgap between the excited state singlet energy level
S.sub.1.sup.TD and the excited state triplet energy level
T.sub.1.sup.TD of the first dopant may be equal to or less than
about 0.3 eV in order to implement a delayed fluorescence.
In addition, an energy level bandgap (|HOMO.sup.H1-HOMO.sup.TD|)
between a HOMO energy level (HOMO.sup.H1) of the first host and a
HOMO energy level (HOMO.sup.TD) of the first dopant, or an energy
level bandgap (|LUMO.sup.H1-LUMO.sup.TD|) between a LUMO energy
level (LUMO.sup.H1) of the first host and a LUMO energy level
(LUMO.sup.TD) of the first dopant may be equal to or less than
about 0.5 eV.
Each of the EML1 562, the EML2 564 and the EML3 566 may include the
first host, the second host and the third host, respectively. For
example, each of the first to third hosts may be the same or
different from each other. For Example, each of the first to third
hosts may independently include, but is not limited to, mCP-CN,
CBP, mCBP, mCP, DPEPO, PPT, TmPyPB, PYD-2Cz, DCzDBT, DCzTPA,
pCzB-2CN, mCzB-2CN, TSPO1, CCP,
9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9'-bicarbazole and/or
4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.
Each of the second and third dopants may have narrow FWHM and have
luminous spectrum having large overlapping area with the absorption
spectrum of the first dopant. As an example, each of the second and
third dopants may independently include, but is not limited to, an
organic compound having a quinolino-acridine core such as
5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
5,12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
5,12-dibutyl-3,10-difluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, DCJTB and any metal complexes which can emit light of
green color.
In one exemplary embodiment, each of the first to third hosts in
the EML1 562, EML2 564 and the EML3 566 may have weigh ratio equal
to or more than the weight ratio of the first to third dopants
within the same EMLs 562, 564 and 566. The weight ratio of the
first dopant in the EML1 562 may be more than each of the weight
ratio of the second and third dopants in the EML2 564 and the EML3
566. In this case, it is possible to transfer enough exciton energy
from the first dopant in the EML1 562 to the second and third
dopants in the EML2 564 and the EML3 566 through FRET energy
transfer mechanism.
Particularly, the weight ratio of the first host may be equal to or
more than the weight ratio of the first dopant in the EML1 562. As
an example, the EML1 562 may include the first host of about 50 to
about 99% by weight, preferably about 60 to about 90% by weight,
and more preferably about 60 to about 80% by weight, and the first
dopant of about 1 to about 50% by weight, preferably about 10 to
about 40% by weight, and more preferably about 20 to about 40% by
weight.
Each of the weight ratios of the second and thirds hosts may be
larger than each of the weight ratios of the second and third
dopants in the EML2 564 and the EML3 566. As an example, each of
the EML2 564 and EML3 566 may include the second or third host, but
is not limited to, about 90 to about 99% by weight, and preferably
about 95 to about 99% by weight, and the second or third dopant,
but is not limited to, about 1 to about 10% by weight, and
preferably about 1 to about 5% by weight.
The EML1 562 may be laminated with a thickness of, but is not
limited to, about 2 nm to about 100 nm, preferably about 2 nm to
about 30 nm, and preferably about 2 to about 20 nm. Each of the
EML2 564 and the EML3 566 may be laminated with a thickness of, but
is not limited to, about 5 nm to about 100 nm, preferably about 10
nm to about 30 nm, and more preferably about 10 nm to about 20
nm.
When the EML2 564 is disposed adjacently to the EBL 555 in one
exemplary embodiment, the second host, which is included in the
EML2 564 together with the second dopant, may be the same material
as the EBL 555. In this case, the EML2 564 may have an electron
blocking function as well as an emission function. In other words,
the EML2 564 can act as a buffer layer for blocking electrons. In
one embodiment, the EBL 555 may be omitted where the EML2 564 may
be an electron blocking layer as well as an emitting material
layer.
When the EML3 566 is disposed adjacently to the HBL 575 in another
exemplary embodiment, the third host, which is included in the EML3
566 together with the third dopant, may be the same material as the
HBL 575. In this case, the EML3 566 may have a hole blocking
function as well as an emission function. In other words, the EML3
566 can act as a buffer layer for blocking holes. In one
embodiment, the HBL 575 may be omitted where the EML3 566 may be a
hole blocking layer as well as an emitting material layer.
In still another exemplary embodiment, the second host in the EML2
564 may be the same material as the EBL 555 and the third host in
the EML3 566 may be the same material as the HBL 575. In this
embodiment, the EML2 564 may have an electron blocking function as
well as an emission function, and the EML3 566 may have a hole
blocking function as well as an emission function. In other words,
each of the EML2 564 and the EML3 566 can act as a buffer layer for
blocking electrons or hole, respectively. In one embodiment, the
EBL 555 and the HBL 575 may be omitted where the EML2 564 may be an
electron blocking layer as well as an emitting material layer and
the EML3 566 may be a hole blocking layer as well as an emitting
material layer.
In the above embodiments, the OLED having only one emitting unit is
described. Unlike the above embodiment, the OLED may have multiple
emitting units so as to form a tandem structure. FIG. 11 is a
cross-sectional view illustrating an organic light emitting diode
in accordance with still another embodiment of the present
disclosure.
As illustrated in FIG. 11, the OLED 600 in accordance with the
fifth embodiment of the present disclosure includes first and
second electrodes 610 and 620 facing each other, a first emitting
unit 630 as a first emission layer disposed between the first and
second electrodes 610 and 620, a second emitting unit 730 as a
second emission layer disposed between the first emitting unit 630
and the second electrode 620, and a charge generation layer 710
disposed between the first and second emitting units 630 and
730.
As mentioned above, the first electrode 610 may be an anode and
include, but is not limited to, a conductive material having a
relatively large work function values. As an example, the first
electrode 610 may include, but is not limited to, ITO, IZO, SnO,
ZnO, ICO, AZO, and the like. The second electrode 620 may be a
cathode and may include, but is not limited to, a conductive
material having a relatively small work function values such as Al,
Mg, Ca, Ag, alloy thereof or combination thereof. Each of the first
and second electrodes 610 and 620 may be laminated with a thickness
of, but is not limited to, about 30 nm to about 300 nm.
The first emitting unit 630 includes a HIL 640, a first HTL (a
lower HTL) 650, a lower EML 660 and a first ETL (a lower ETL) 670.
The first emitting unit 630 may further include a first EBL (a
lower EBL) 655 disposed between the first HTL 650 and the lower EML
660 and/or a first HBL (a lower HBL) 675 disposed between the lower
EML 660 and the first ETL 670.
The second emitting unit 730 includes a second HTL (an upper HTL)
750, an upper EML 760, a second ETL (an upper ETL) 770 and an EIL
780. The second emitting unit 730 may further include a second EBL
(an upper EBL) 755 disposed between the second HTL 750 and the
upper EML 760 and/or a second HBL (an upper HBL) 775 disposed
between the upper EML 760 and the second ETL 770.
At least one of the lower EML 660 and the upper EML 760 may include
the organic compound having the structure of any one in Chemical
Formulae 1, 4, 7, 8 and 11 and emit green (G) light. As an example,
one of the lower and upper EMLs 660 and 760 may emit green (G)
light, and the other of the lower and upper EMLs 660 and 760 may
emit blue (B) and/or red (R) light. Hereinafter, the OLED 600,
where the lower EML 660 emits green light and includes the organic
compound having the structure of any one in Chemical Formulae 1, 4,
7, 8 and 11 and the upper EML 760 emits blue and/or red lights,
will be explained.
The HIL 640 is disposed between the first electrode 610 and the
first HTL 650 and improves an interface property between the
inorganic first electrode 610 and the organic first HTL 650. In one
exemplary embodiment, the HIL 640 may include, but is not limited
to, MTDATA, NATA, 1T-NATA, 2T-NATA, CuPc, TCTA, NPB(NPD), HAT-CN,
TDAPB, PEDOT/PSS and/or
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine. The HIL 640 may be omitted in compliance with a
structure of the OLED 600.
Each of the first and second HTLs 650 and 750 may independently
include, but is not limited to, TPD, NPD(NPB), CBP, poly-TPD, TFB,
TAPC,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluoren-2-amine and/or
N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine-
. Each of the HIL 640 and the first and second HTLs 650 and 750 may
be laminated with a thickness of, but is not limited to, about 5 nm
to about 200 nm, and preferably about 5 nm to about 100 nm.
Each of the first and second ETLs 670 and 770 facilitates electron
transportations in the first emitting unit 630 and the second
emitting unit 730, respectively. Each of the first and second ETLs
670 and 770 may independently include, but is not limited to,
oxadiazole-based compounds, triazole-based compounds,
phenanthroline-based compounds, benzoxazole-based compounds,
benzothiazole-based compounds, benzimidazole-based compounds,
triazine-based compounds, and the like, respectively. As an
example, each of the first and second ETLs 670 and 770 may
independently include, but is not limited to, Alq.sub.3, PBD,
spiro-PBD, Liq, TPBi, BAlq, Bphen, NBphen, BCP, TAZ, NTAZ, TpPyPB,
TmPPPyTz, PFNBr and/or TPQ, respectively.
The EIL 780 is disposed between the second electrode 620 and the
second ETL 770, and can improve physical properties of the second
electrode 620 and therefore, can enhance the life span of the OLED
600. In one exemplary embodiment, the EIL 780 may include, but is
not limited to, an alkali halide such as LiF, CsF, NaF, BaF.sub.2
and the like, and/or an organic metal compound such as lithium
benzoate, sodium stearate, and the like.
As an example, each of the first and second EBLs 655 and 755 may
independently include, but is not limited to, TCTA,
Tris[4-(diethylamino)phenyl]amine,
N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-
-fluorene-2-amine, TAPC, MTDATA, mCP, mCBP, CuPc, DNTPD, TDAPB
2,8-bis(9-phneyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene and/or
3,6-bis(N-carbazolyl)-N-phenyl-carbazole, respectively.
Each of the first and second HBLs 675 and 775 may independently
include, but is not limited to, oxadiazole-based compounds,
triazole-based compounds, phenanthroline-based compounds,
benzoxazole-based compounds, benzothiazole-based compounds,
benzimidazole-based compounds, and triazine-based compounds. As an
example, each of the first and second HBLs 675 and 775 may
independently include, but is not limited to, BCP, BAlq, Alga, PBD,
spiro-PBD, Liq, B3PYMPM, DPEPO,
9-(6-(9H-carbazol-9-yl)pyridine-3-yl)-9H-3,9'-bicarbazole and
combination thereof, respectively.
In one exemplary embodiment, when the upper EML 760 emits red
light, the upper EML 760 may be, but is not limited to, a
phosphorescent material layer including a host such as CBP and the
like and at least one dopant selected from the group consisting of
PIQIr(acac) (bis(1-phenylisoquinoline)acetylacetonate iridium).
PQIr(acac) (bis(1-phenylquinoline)acetylacetonate iridium), PQIr
(tris(1-phenylquinoline)iridium) and PtOEP(octaethylporphyrin
platinum). Alternatively, the upper EML 760 may be a fluorescent
material layer including PBD:Eu(DMB).sub.3(phen), perylene and/or
their derivatives. In this case, the upper EML 760 may emit red
light having, but is not limited to, emission wavelength ranges of
about 600 nm to about 650 nm.
In another exemplary embodiment, when the upper EML 760 emits blue
light, the upper EML 760 may be, but is not limited to, a
phosphorescent material layer including a host such as CBP and the
like and at least one iridium-based dopant. Alternatively, the
upper EML 760 may be a fluorescent material layer including any one
selected from the group consisting of spiro-DPVBi, spiro-CBP,
distrylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and
PPV-based polymers. The upper EML 760 may emit light of sky-blue
color or deep blue color as well as blue color. In this case, the
upper EML 760 may emit red light having, but is not limited to,
emission wavelength ranges of about 440 nm to about 480 nm.
In one exemplary embodiment, the second emitting unit 730 may have
double-layered EML 760, for example, a blue emitting material layer
and a red emitting material layer, in order to enhance luminous
efficiency of the red light. In this case, the upper EML 760 may
emit light having, but is not limited to, emission wavelength
ranges of about 440 nm to about 650 nm.
The charge generation layer (CGL) 710 is disposed between the first
emitting unit 630 and the second emitting unit 730. The CGL 710
include an N-type CGL 810 disposed adjacently to the first emitting
unit 630 and a P-type CGL 820 disposed adjacently to the second
emitting unit 730. The N-type CGL 810 injects electrons into the
first emitting unit 630 and the P-type CGL 820 injects holes into
the second emitting unit 730.
As an example, the N-type CGL 810 may be a layer doped with an
alkali metal such as Li, Na, K and/or Cs and/or an alkaline earth
metal such as Mg, Sr, Ba and/or Ra. For example, a host used in the
N-type CGL 810 may include, but is not limited to, an organic
compound such as Bphen or MTDATA. The alkali metal or the alkaline
earth metal may be doped by about 0.01 wt % to about 30 wt %.
The P-type CGL 820 may include, but is not limited to, an inorganic
material selected from the group consisting of tungsten oxide
(WO.sub.x), molybdenum oxide (MoO.sub.x), beryllium oxide
(Be.sub.2O.sub.3), vanadium oxide (V.sub.2O.sub.5) and combination
thereof, and/or an organic material selected from the group
consisting of NPD, HAT-CN,
2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), TPD,
N,N,N',N'-Tetranaphthalenyl-benzidine (TNB), TCTA,
N,N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) and
combination thereof.
The lower EML 660 includes a first EML (EML1) 662 disposed between
the first EBL 655 and the first HBL 675, a second EML (EML2) 664
disposed between the first EBL 655 and the EML1 662 and a third EML
(EML3) 666 disposed between the EML1 662 and the first HBL 675. The
EML1 662 includes a first dopant (T dopant) which is a delayed
fluorescent material. i.e. the organic compound having the
structure of any one in Chemical Formulae 1, 4, 7, 8 and 11. Each
of the EML2 664 and the EML3 666 includes a second dopant (a first
F dopant) and a third dopant (a second F dopant) each of which is a
fluorescent or phosphorescent material, respectively. Each of the
EML1 662, the EML2 664 and the EML3 666 includes a first host, a
second host and a third host, respectively.
In this case, the singlet exciton energy as well as the triplet
exciton energy of the first dopant in the EML1 662 can be
transferred to each of the second and third dopants each of which
is included in the EML2 664 and EML3 666 disposed adjacently to the
EML1 662 by FRET energy transfer mechanism. Accordingly, the
ultimate emission occurs in the second and third dopants in the
EML2 664 and the EML3 666.
In other words, the triplet exciton energy of the first dopant is
converted to the singlet exciton energy of its own in the EML1 662
by RISC mechanism, then the singlet exciton energy of the first
dopant is transferred to each of the singlet exciton energy of the
second and third dopants because the excited state singlet energy
level S.sub.1.sup.TD of the first dopant is higher than each of the
excited state singlet energy levels S.sub.1.sup.FD1 and
S.sub.1.sup.FD2 of the second and third dopants (See, FIG. 10).
The second and third dopants in the EML2 664 and EML3 666 can emit
light using the singlet exciton energy and the triplet exciton
energy derived from the first dopant. Since the second and third
dopants have relatively narrow FWHM as compared with the first
dopant, the OLED 600 can enhance its luminous efficiency and color
purity.
Each of the EML1 662, the EML2 664 and the EML3 666 includes the
first host, the second host and the third host, respectively. For
example, each of the first to third hosts may be the same or
different from each other. As an example, each of the first to
third hosts may independently include, but is not limited to,
mCP-CN, CBP, mCBP, mCP, DPEPO, PPT, TmPyPB, PYD-2Cz, DCzDBT,
DCzTPA, pCzB-2CN, mCzB-2CN, TSPO1, CCP,
9-(4-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole,
9-(6-(9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9'-bicarbazole and/or
4-(3-(triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene.
Each of the second and third dopants may have narrow FWHM and have
luminous spectrum having large overlapping area with the absorption
spectrum of the first dopant. As an example, each of the second and
third dopants may independently include, but is not limited to, an
organic compound having a quinolino-acridine core such as
5,12-dimethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
5,12-diethylquinolino[2,3-b]acridine-7,14(5H, 12H)-dione,
5,12-dibutyl-3,10-di fluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-3,10-bis(trifluoromethyl)quinolino[2,3-b]acridine-7,14(5H,
12H)-dione,
5,12-dibutyl-2,3,9,10-tetrafluoroquinolino[2,3-b]acridine-7,14(5H,
12H)-dione, DCJTB and any metal complexes which can emit light of
green color.
In this case, the energy levels among the first to third hosts and
the first to third dopant within the lower EML 660 are the same as
described in FIG. 10.
In one exemplary embodiment, each of the first to third hosts in
the EML1 662, EML2 664 and the EML3 666 may have weigh ratio equal
to or more than the weight ratio of the first to third dopants
within the same EMLs 662, 664 and 666. The weight ratio of the
first dopant in the EML1 662 may be more than each of the weight
ratio of the second and third dopants in the EML2 664 and the EML3
666. In this case, it is possible to transfer enough exciton energy
from the first dopant in the EML1 662 to the second and third
dopants in the EML2 664 and the EML3 666 through FRET energy
transfer mechanism.
When the EML2 664 is disposed adjacently to the first EBL 655 in
one exemplary embodiment, the second host, which is included in the
EML2 664 together with the second dopant, may be the same material
as the first EBL 655. In this case, the EML2 664 may have an
electron blocking function as well as an emission function. In
other words, the EML2 664 can act as a buffer layer for blocking
electrons. In one embodiment, the first EBL 655 may be omitted
where the EML2 664 may be an electron blocking layer as well as an
emitting material layer.
When the EML3 666 is disposed adjacently to the first HBL 675 in
another exemplary embodiment, the third host, which is included in
the EML3 666 together with the third dopant, may be the same
material as the first HBL 675. In this case, the EML3 666 may have
a hole blocking function as well as an emission function. In other
words, the EML3 666 can act as a buffer layer for blocking holes.
In one embodiment, the first HBL 675 may be omitted where the EML3
666 may be a hole blocking layer as well as an emitting material
layer.
In still another exemplary embodiment, the second host in the EML2
664 may be the same material as the first EBL 655 and the third
host in the EML3 666 may be the same material as the first HBL 675.
In this embodiment, the EML2 664 may have an electron blocking
function as well as an emission function, and the EML3 666 may have
a hole blocking function as well as an emission function. In other
words, each of the EML2 664 and the EML3 666 can act as a buffer
layer for blocking electrons or hole, respectively. In one
embodiment, the first EBL 655 and the first HBL 675 may be omitted
where the EML2 664 may be an electron blocking layer as well as an
emitting material layer and the EML3 666 may be a hole blocking
layer as well as an emitting material layer.
In an alternative embodiment, the lower EML 660 may have a
single-layered structure as illustrated in FIGS. 2 and 5. In this
case, the lower EML 660 may include a host and a first dopant which
may be a delayed fluorescent material, i.e. the organic compound
having the structure of any one in Chemical Formulae 1, 4, 7, 8 and
11. Alternatively, the lower EML 660 may include a host, a first
dopant which may be a delayed fluorescent material and a second
dopant which may be a fluorescent or phosphorescent material.
In another alternative embodiment, the lower EML 660 may have a
double-layered structure as illustrated in FIG. 7. In this case,
the lower EML 660 may include a first EML and a second EML. The
first EML may include a first host and a first dopant which may be
a delayed fluorescent material, i.e. the organic compound having
the structure of any one in Chemical Formulae 1, 4, 7, 8 and 11,
and the second EML may include a second host and a second dopant
which may be a fluorescent or phosphorescent material.
In another exemplary embodiment, an OLED of the present disclosure
may further includes a third emitting unit disposed between the
second emitting unit 730 and the second electrode 620 and a second
CGL disposed between the second emitting unit 730 and the third
emitting unit. In this case, at least one of the first emitting
unit 630, the second emitting unit 730 and the third emitting unit
may include the organic compound having the structure of any one in
Chemical Formulae 1, 4, 7, 8 and 11 as the dopant.
Synthesis Example 1: Synthesis of Compound 1-2
(1) Synthesis of Intermediate A1
##STR00039##
10 g (1 equivalent) of 2-chloro-4,6-diphenyl-1,3,5-triazine was
dissolved in 80 mL of 1,4-dioxane with stirring under nitrogen
atmosphere. 28.46 g (3 equivalents) of bis(pinacolato)diboron, 1 g
(0.03 equivalent) of tris(dibenzylideneacetone) dipalladium (0)
(Pd.sub.2(dba).sub.3), 0.24 g (0.1 equivalent) of
2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (Xphos) and
11 g (3 equivalents) of potassium acetate were added into the
solution, and then the solution was refluxed with stirring for more
than 12 hours to proceed a reaction. After the reaction was
completed, the solution was cooled down to room temperature, was
extracted with ethyl acetate and distilled water, and then
MgSO.sub.4 was added into the organic solution to remove moisture.
A crude extract was separated and isolated by column chromatography
using hexane and ethyl acetate (4:1) as a developing solvent and
was re-crystallized to give 10.2 g of Intermediate A1 (yield:
72%).
(2) Synthesis of Intermediate A2
##STR00040##
19.24 g (5 equivalents) of potassium carbonate was dissolved in 50
mL of water. 10 g (1 equivalent) of Intermediate A1, 8.35 g (1.5
equivalents) of 2-bromo-5-fluorobenzonitrile, 1.61 g (0.05
equivalent) of tetrakis(triphenylphosphine) palladium (0)
(Pd(PPh.sub.3).sub.4) and 150 mL of THF was added into the aqueous
solution, and then the mixed solution was refluxed with stirring
for more than 96 hours to proceed to a reaction. After the reaction
was completed, the solution was cooled down to room temperature,
was extracted with ethyl acetate and distilled water, and then
MgSO.sub.4 was added into the organic solution to remove moisture.
A crude extract was separated and purified by column chromatography
using hexane and methylene chloride (3:1) as a developing solvent
and was re-crystallized to give 6.4 g of Intermediate A2 (yield:
65%).
(3) Synthesis of Intermediate D1
##STR00041##
10 g (1 equivalent) of 1-bromo-2-iodobenzene, 3.6 mL (1 equivalent)
of aniline, 0.4 g (0.05 equivalent) of Pd.sub.2(dba).sub.3, 1 mL
(0.1 equivalent) of tri-tert-butylphosphine and 5.1 g (5
equivalents) of sodium-tert-butoxide was suspended in 120 mL of
toluene, and then the suspension was refluxed with stirring for 20
hours. After the reaction was completed, the suspension was
extracted with methylene chloride and distilled water and then
organic layer was distilled under reduced pressure. A crude extract
was separated and purified by column chromatography using hexane
and methylene chloride (5:1) as a developing solvent and was
re-crystallized to give 7.5 g of Intermediate D1 (yield: 85%).
(4) Synthesis of Intermediate D2
##STR00042##
7.5 g of intermediate D1 was added into 80 mL of THF under nitrogen
atmosphere, and then the solution was cooled down to -78.degree. C.
using dry ice. 24 mL of 2.5 M n-BuLi was added into the solution
drop wisely and then the solution was stirred for 1 hour. 5.88 g of
xanthone dissolved in 50 mL of THF was added into the solution.
After removing solvents, 100 mL of acetic acid/HCl (1:10 v/v) was
added to give 8.35 g of Intermediate D2 (yield: 80%).
(5) Synthesis of Compound 1-2
##STR00043##
1.92 g (1.3 equivalents) of Intermediate D2 was placed into a
reaction vessel under nitrogen atmosphere, then 50 mL of dimethyl
formamide was added into the reaction vessel, and then the solution
was stirred. 0.74 g (3 equivalents) of sodium hydride (55%)
dispersed in paraffin was added into the solution. After the
solution was stirred enough to generate hydrogen gas, 1.50 g of
intermediate A2 was added into the solution, and the solution was
refluxed with stirring for more than 96 hours at 160.degree. C. The
solution was cooled down to room temperature, dimethyl formamide
was evaporated and then the solution was filtered with toluene. A
crude product was separated and purified by column chromatography
using hexane and toluene (1:3) as a developing solvent and was
re-crystallized to give 1.15 g of white solid Compound 1-2 (yield:
74%).
Synthesis Example 2: Synthesis of Compound 1-16
(1) Synthesis of Intermediate A3
##STR00044##
g (4 equivalents) of potassium carbonate was dissolved in 30 mL of
water. 5 g (1 equivalent) of intermediate A1, 3.34 g (1.2
equivalents) of 5-bromo-2-fluorobenzonitrile, 0.85 g (0.05
equivalent) of Pd(PPh.sub.3).sub.4 and 90 mL of THF was added into
the aqueous solution, and then the mixed solution was refluxed with
stirring for more than 96 hours to proceed to a reaction. After the
reaction was completed, the solution was cooled down to room
temperature, was extracted with ethyl acetate and distilled water,
and then MgSO.sub.4 was added into the solution to remove moisture.
A crude extract was separated and purified by column chromatography
using hexane and methylene chloride (3:1) as a developing solvent
and was re-crystallized to give 3.8 g of Intermediate A3 (yield:
78%).
(2) Synthesis of Intermediate D3
##STR00045##
7.5 g of intermediate D1 was added into 80 mL of THF under nitrogen
atmosphere, and then the solution was cooled down to -78.degree. C.
using dry ice. 24 mL of 2.5 M n-BuLi was added into the solution
drop wisely and then the solution was stirred for 1 hour. 5.6 g of
9-fluorneone dissolved in 50 mL of THF wad added into the solution.
After removing solvents, 100 mL of acetic acid/HCl (1:10 v/v) was
added to give 7.19 g of Intermediate D3 (yield: 78%).
(3) Synthesis of Compound 1-16
##STR00046##
2.11 g (1.5 equivalents) of Intermediate D3 was placed into a
reaction vessel under nitrogen atmosphere, then 50 mL of dimethyl
formamide was added into the reaction vessel, and then the solution
was stirred. 0.74 g (3 equivalents) of sodium hydride (55%)
dispersed in paraffin was added into the solution. After the
solution was stirred enough to generate hydrogen gas, 1.50 g (1
equivalent) of Intermediate A3 was added into the solution, and the
solution was refluxed with stirring for more than 96 hours at
160.degree. C. The solution was cooled down to room temperature,
dimethyl formamide was evaporated and then the solution was
filtered with toluene. A crude product was separated and purified
by column chromatography using hexane and toluene (1:3) as a
developing solvent and was re-crystallized to give 1.27 g of white
solid Compound 1-16 (yield: 82%).
Synthesis Example 3: Synthesis of Compound 1-17
##STR00047##
1.92 g (1.3 equivalents) of Intermediate D2 was placed into a
reaction vessel under nitrogen atmosphere, then 50 mL of dimethyl
formamide was added into the reaction vessel, and then the solution
was stirred. 0.74 g (3 equivalents) of sodium hydride (55%)
dispersed in paraffin was added into the solution. After the
solution was stirred enough to generate hydrogen gas, 1.50 g of
Intermediate A3 was added into the solution, and the solution was
refluxed with stirring for more than 96 hours at 160.degree. C. The
solution was cooled down to room temperature, dimethyl formamide
was evaporated and then the solution was filtered with toluene. A
crude product was separated and purified by column chromatography
using hexane and toluene (1:3) as a developing solvent and was
re-crystallized to give 1.11 g of white solid Compound 1-17 (yield:
71%).
Synthesis Example 4: Synthesis of Compound 2-1
(1) Synthesis of Intermediate A4
##STR00048##
8.65 g (4.5 equivalents) of potassium carbonate was dissolved in 30
mL of water. 5 g (1 equivalent) of Intermediate A1, 3.76 g (1.2
equivalents) of 5-bromo-2-fluoroisophthalonitrile, 1.19 g (0.07
equivalent) of Pd(PPh.sub.3).sub.4 and 80 mL of THF was added into
the aqueous solution, and then the mixed solution was refluxed with
stirring for more than 96 hours to proceed to a reaction. After the
reaction was completed, the solution was cooled down to room
temperature, was extracted with ethyl acetate and distilled water,
and then MgSO.sub.4 was added into the organic solution to remove
moisture. A crude extract was separated and purified by column
chromatography using hexane and methylene chloride (5:2) as a
developing solvent and was re-crystallized to give 3.8 g of white
solid Intermediate A4 (yield: 78%).
(2) Synthesis of Compound 2-1
##STR00049##
2.1 g (1.5 equivalents) of Intermediate D3 was placed into a
reaction vessel under nitrogen atmosphere, then 50 mL of dimethyl
formamide was added into the reaction vessel, and then the solution
was stirred. 0.74 g (3 equivalents) of sodium hydride (55%)
dispersed in paraffin was added into the solution. After the
solution was stirred enough to generate hydrogen gas, 1.60 g (1
equivalent) of Intermediate A4 was added into the solution, and the
solution was refluxed with stirring for more than 96 hours at
160.degree. C. The solution was cooled down to room temperature,
dimethyl formamide was evaporated and then the solution was
filtered with toluene. A crude product was separated and purified
by column chromatography using hexane and toluene (2:5) as a
developing solvent and was re-crystallized to give 0.89 g of white
solid Compound 2-1 (yield: 57%).
Experimental Example 1: Evaluation of Energy Levels
Energy levels for the Compounds in the Synthesis Examples 1 to 4
were evaluated. Particularly, HOMO energy level, LUMO energy level
and energy level bandgap (Eg)) for each of the compounds were
evaluated. For the comparison, energy levels for the following
referenced compounds were also evaluated. The evaluation results
are indicated in the following table 1. As indicated by Table 1,
each of Compounds in the Synthesis Examples 1 to 4 showed an
adequate HOMO energy level, LUMO energy level and energy level
bandgap as used a luminous material, i.e. a dopant in an emitting
layer of an organic light emitting diode.
Referenced Compounds
##STR00050##
TABLE-US-00001 TABLE 1 Energy Levels of Organic Compound Compound
HOMO (eV) LUMO (eV) Eg (eV) Ref. 1 -5.3 -2.5 2.80 Ref. 2 -5.2 -2.4
2.84 Ref. 3 -5.3 -2.6 2.75 Compound 1-2 -5.3 -2.7 2.68 Compound
1-16 -5.4 -2.8 2.66 Compound 1-17 -5.4 -2.7 2.70 Compound 2-1 -5.5
-2.8 2.72 HOMO: Film (100 nm/ITO), by AC3, LUMO: calculated from
film absorption edge; Eg: LUMO-HOMO
Example 1: Fabrication of Organic Light Emitting Diode (OLED)
An organic light emitting diode was fabricated using Compound 1-2
synthesized in the Synthesis Example 1 as a dopant in an emitting
material layer (EML). An ITO substrate was treated with UV ozone
and then loaded into an evaporation system. The cleaned substrate
was transferred to a deposition chamber in order to deposit other
layers on the substrate. An organic layer was deposited by
evaporation by a heated boat under 10.sup.-6 torr in the following
order:
A hole injection layer (HIL) (HAT-CN; 7 nm); a hole transport layer
(HTL) (NPB, 55 nm); an electron blocking layer (EBL) (mCBP; 10 nm);
an emitting material layer (EML)
(4-(3-triphenylen-2-yl)phenyl)dibenzo[b,d]thiophene (host):
Compound 1-2 (dopant)=70:30 by weight ratio; 35 nm); a hole
blocking layer (HBL) (B3PYMPM; 10 nm); an electron transport layer
(ETL) (TPBi; 20 nm); an electron injection layer (EIL) (LiF); and a
cathode (Al).
And then, capping layer (CPL) was deposited over the cathode and
the device was encapsualted by glass. After deposition of emissve
layer and the cathode, the OLED was transferred from the depostion
chamber to a dry box for film formation, followed by encapsulation
using UV-curable epoxy and moisture getter. The manufactured
organic light emitting diode had an emision area of 9 mm.sup.2.
Examples 2 to 4: Fabrication of OLED
An organic light emitting diode was manufactured as the same
process and the same materials as Example 1, except using compound
1-16 (Example 2), Compound 1-17 (Example 3) or Compound 2-1
(Example 4) as the dopant in place of Compound 1-2 in the EML.
Comparative Examples 1 to 3: Manufacture of OLED
An organic light emitting diode was manufactured as the same
process and the same materials as Example 1, except using Ref 1
(Comparative Example 1; Ref. 1), Ref. 2 (Comparative Example 2;
Ref. 2) or Ref. 3 (Comparative Example 3; Ref. 3) as the dopant in
placed of Compound 1-2 in the EML.
Experimental Example 2: Measurement of Luminous Properties of
OLED
Each of the organic light emitting diodes fabricated in Examples 1
to 4 and Comparative Examples 1 to 3 was connected to an external
power source and then luminous properties for all the diodes were
evaluated using a constant current source (KEITHLEY) and a
photometer PR650 at room temperature. In particular, current
efficiency (cd/A), external quantum efficiency (EQE; %), maximum
electroluminescence wavelength (EL .lamda..sub.max; nm) and color
coordinates at a current density of 10 mA/cm.sup.2 for the OLEDs
were measured. The results thereof are shown in the following Table
2.
TABLE-US-00002 TABLE 2 Luminous Properties of OLED Sample cd/A EQE
(%) EL .lamda..sub.max (nm) CIE Ref. 1 3.99 2.17 480 (0.168, 0.260)
Ref. 2 7.88 4.80 468 (0.156, 0.224) Ref. 3 19.14 6.51 514 (0.258,
0.491) Example 1 56.90 17.40 520 (0.325, 0.512) Example 2 73.10
21.65 528 (0.330, 0.521) Example 3 61.10 18.73 520 (0.327, 0.516)
Example 4 45.64 15.03 518 (0.291, 0.546)
As indicated in Table 2, compared with the OLED using organic
compounds having a triazine core as the dopant in the EML of the
Comparative Examples, the OLED using the organic compounds of the
present disclosure as the dopant in the EML of the Examples
improved its current efficiency up to 17.32 times and EQE up to
8.98 times. Compared to the OLED using the compounds having a Spiro
moiety substituted with cyano group as the dopant in the
Comparative Examples 2 and 3, the OLED using the organic compound
of the present disclosure as the dopant in the Examples improved
its current efficiency up to 8.28 times and EQE up to 3.51 times.
Also, compared the EL .lamda..sub.max and CIEs in the Examples with
the EL .lamda..sub.max and CIEs in the Comparative Examples, it was
confirmed that the OLEDs in the Examples 1-4 emit light having a
deeper green color. It was confirmed that the OLED can implement
hyper-fluorescence having enhanced luminous efficiency and high
color purity by applying the organic compounds of the present
disclosure into an emission layer.
While the present disclosure has been described with reference to
exemplary embodiments and examples, these embodiments and examples
are not intended to limit the scope of the present disclosure.
Rather, it will be apparent to those skilled in the art that
various modifications and variations can be made in the present
disclosure without departing from the spirit or scope of the
invention. Thus, it is intended that the present disclosure cover
the modifications and variations of the present disclosure provided
they come within the scope of the appended claims and their
equivalents.
The various embodiments described above can be combined to provide
further embodiments. All of the U.S. patents, U.S. patent
application publications, U.S. patent applications, foreign
patents, foreign patent applications and non-patent publications
referred to in this specification and/or listed in the Application
Data Sheet are incorporated herein by reference, in their entirety.
Aspects of the embodiments can be modified, if necessary to employ
concepts of the various patents, applications and publications to
provide yet further embodiments.
These and other changes can be made to the embodiments in light of
the above-detailed description. In general, in the following
claims, the terms used should not be construed to limit the claims
to the specific embodiments disclosed in the specification and the
claims, but should be construed to include all possible embodiments
along with the full scope of equivalents to which such claims are
entitled. Accordingly, the claims are not limited by the
disclosure.
* * * * *